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Mycoremediation of PAH-contaminated soil
Abstract
Out of a number of white-rot fungal cultures, strains of Irpex lacteus and Pleurotus ostreatus were selected for degradation of 7 three- and four-ring unsubstituted aromatic hydrocarbons (PAH) in two contaminated industrial soils. Respective data for removal of PAH in the two industrial soils by I. lacteus were: fluorene (41 and 67%), phenanthrene (20 and 56%), anthracene (29 and 49%), fluoranthene (29 and 57%), pyrene (24 and 42%), chrysene (16 and 32%) and benzo[a]anthracene (13 and 20%). In the same two industrial soils P. ostreatus degraded the PAH with respective removal figures of fluorene (26 and 35%), phenanthrene (0 and 20%), anthracene (19 and 53%), fluoranthene (29 and 31%), pyrene (22 and 42%), chrysene (0 and 42%) and benzo[a]anthracene (0 and 13%). The degradation of PAH was determined against concentration of PAH in non-treated contaminated soils after 14 weeks of incubation. The fungal degradation of PAH in soil was studied simultaneously with ecotoxicity evaluation of fungal treated and non-treated contaminated soils. Compared to non-treated contaminated soil, fungus-treated soil samples indicated decrease in inhibition of bioluminescence in luminescent bacteria (Vibrio fischerii) and increase in germinated mustard (Brassica alba) seeds.
... However, several oxygenated PAHs metabolites can be accumulated in the environment producing a negative impact in soil as well as human health due to their toxic and carcinogenic properties [4,17,18]. For this reason, only the determination of PAHs reduction after a mycoremediation process is not enough to assess the soil remediation process [19]. Hence, it is recommended to conduct a proper chemical analysis in combination with ecotoxicological assessment of mycoremediated soil by bioassays with different soil organisms (microorganisms, invertebrates, and plants) for a comprehensive assessment of the PAHs mycoremediation results. ...
... In contrast, some other related studies provide a comprehensive assessment of the bioremediation of PAH-polluted soil using ecotoxicological tests. Several ecotoxicological tests have been used to determine the recovery level of soil by mycoremediation such as acute and reproduction toxicity test [9,13,20,21], soil enzymatic activity [9,11,12,22], germination test [10,12,13,15,19,21,23,24], genotoxicity test [14], or inhibition of bioluminescence test [19]. ...
... In contrast, some other related studies provide a comprehensive assessment of the bioremediation of PAH-polluted soil using ecotoxicological tests. Several ecotoxicological tests have been used to determine the recovery level of soil by mycoremediation such as acute and reproduction toxicity test [9,13,20,21], soil enzymatic activity [9,11,12,22], germination test [10,12,13,15,19,21,23,24], genotoxicity test [14], or inhibition of bioluminescence test [19]. ...
Mycoremediation of soils polluted with polycyclic aromatic hydrocarbons (PAHs) is an effective approach in environmental biotechnology to restore ecosystems. In this protocol, we describe selected experimental procedures to assess the mycoremediation process of PAH-polluted soils using chemical and ecotoxicological methodologies. An analytical procedure is described to quantify the removal of PAHs. Additionally, a battery of ecotoxicological assays focused on soil microbial activity, survival and reproduction of invertebrates, and seed germination is also described.
... To that end, scientists have been investigating strategies of remediation with fungi, known as mycoremediation, ever since 1985 when the fungus Phanerochaete chrysosporium was found to be effective at degrading a variety of important environmental pollutants (Bumpus 1989). Since that time, a number of species of fungi including Irpex lacteus, Pleurotus ostreatus, Trametes versicolor, Bjerkandera adusta, Lentinula edodes, Coriolopsis polysona, Cladosporium resinae, and others have demonstrated the ability to degrade a variety of environmental pollutants (Bhatt et al. 2002;Singh 2006). Pollutants that have been successfully targeted for mycoremediation include polycyclic aromatic hydrocarbons (PAHs) (Bhatt et al. 2002;Singh 2006), polychlorinated biphenyls (PCBs) (Šašek et al. 1993), dioxanes and dioxins (Bhatt et al. 2002;Singh 2006), monoaromatics (benzene and toluene) (Pointing 2001), ammunitions (Kaplan 1992;Bennett 1994), and diesel fuel (Batelle 2000). ...
... Since that time, a number of species of fungi including Irpex lacteus, Pleurotus ostreatus, Trametes versicolor, Bjerkandera adusta, Lentinula edodes, Coriolopsis polysona, Cladosporium resinae, and others have demonstrated the ability to degrade a variety of environmental pollutants (Bhatt et al. 2002;Singh 2006). Pollutants that have been successfully targeted for mycoremediation include polycyclic aromatic hydrocarbons (PAHs) (Bhatt et al. 2002;Singh 2006), polychlorinated biphenyls (PCBs) (Šašek et al. 1993), dioxanes and dioxins (Bhatt et al. 2002;Singh 2006), monoaromatics (benzene and toluene) (Pointing 2001), ammunitions (Kaplan 1992;Bennett 1994), and diesel fuel (Batelle 2000). ...
... Since that time, a number of species of fungi including Irpex lacteus, Pleurotus ostreatus, Trametes versicolor, Bjerkandera adusta, Lentinula edodes, Coriolopsis polysona, Cladosporium resinae, and others have demonstrated the ability to degrade a variety of environmental pollutants (Bhatt et al. 2002;Singh 2006). Pollutants that have been successfully targeted for mycoremediation include polycyclic aromatic hydrocarbons (PAHs) (Bhatt et al. 2002;Singh 2006), polychlorinated biphenyls (PCBs) (Šašek et al. 1993), dioxanes and dioxins (Bhatt et al. 2002;Singh 2006), monoaromatics (benzene and toluene) (Pointing 2001), ammunitions (Kaplan 1992;Bennett 1994), and diesel fuel (Batelle 2000). ...
Fungi are well adapted for decomposition processes due to their filamentous growth, extracellular nutrition, and enzymatic capacities. As such, fungi are essential to composting for degrading recalcitrant compounds, stabilizing organic matter, as well as releasing nutrients and essential elements that are beneficial for plant growth and fertility. Here we discuss different composting processes and their associated fungi. We first discuss current research on municipal composting and vermicomposting, and then the history and science of composting for cultivating mushrooms, particularly Agaricus bisporus. At the conclusion of this chapter, we discuss mycoaugmented composts and their use in remediating soils contaminated with a variety of organopollutants and xenobiotic compounds, an area of growing interest and investigation.
... A lot of strains of Aspergillus work as excellent biosorbents for heavy metals removal, including cadmium from oil field water (Barros Ph. chrysosporium Bumpus (1989), Dietrich, 1990 (1992) DTT, lindane Ph. chrysosporium Bumpus (1989) 2,4,6-Trinitrotoluene Ph. chrysosporium Fernando et al. (1990) PAH Xerotus discolor Acevedo et al. (2011) Bjerkandera specie Matsubara et al. (2006) Irpex lacteus Bhatt et al. (2002), Cajthaml et al. (2006) Phellinus sp. Arun and Eyini (2011) Schizophyllum commune Matsubara et al. (2006) Stropharia coronilla Steffen (2000) Pentachlorophenol Agrocybe perfecta, T. villosa, T. hirsuta Machado et al. (2005) Ceriporiopsis subvermispora (Lamar and Dietrich, 1990; (Cernansky et al., 2007) copper, lead, arsenic (Clausen, 2004;Mukherjee et al., 2010), chromium (Prasenjit and Sumathi, 2005;Srivastava and Thakur, 2006). ...
... Such pollutants as DTT, lindane (Bumpus, 1989) and 2,4,6-Trinitrotoluene (Fernando et al., 1990) can also be completely degraded by P. chrysosporium. A high level of polycyclic aromatic hydrocarbon biodegradation was reported for such fungi as Xerotus discolor (Acevedo et al., 2011), Bjerkandera species (Matsubara et al., 2006), Irpex lacteus (Bhatt et al., 2002;Cajthaml et al., 2006), Phellinus sp. (Arun and Eyini, 2011), Schizophyllum commune Fr (Matsubara et al., 2006), Stropharia coronilla (Steffen, 2000). ...
This review presents a comprehensive summary of the latest research in the field of bioremediation with filamentous fungi. The main focus is on the issue of recent progress in remediation of pharmaceutical compounds, heavy metal treatment and oil hydrocarbons mycoremediation that are usually insufficiently represented in other reviews. It encompasses a variety of cellular mechanisms involved in bioremediation used by filamentous fungi, including bio-adsorption, bio-surfactant production, bio-mineralization, bio-precipitation, as well as extracellular and intracellular enzymatic processes. Processes for wastewater treatment accomplished through physical, biological, and chemical processes are briefly described. The species diversity of filamentous fungi used in pollutant removal, including widely studied species of Aspergillus, Penicillium, Fusarium, Verticillium, Phanerochaete and other species of Basidiomycota and Zygomycota are summarized. The removal efficiency of filamentous fungi and time of elimination of a wide variety of pollutant compounds and their easy handling make them excellent tools for the bioremediation of emerging contaminants. Various types of beneficial byproducts made by filamentous fungi, such as raw material for feed and food production, chitosan, ethanol, lignocellulolytic enzymes, organic acids, as well as nanoparticles, are discussed. Finally, challenges faced, future prospects, and how innovative technologies can be used to further exploit and enhance the abilities of fungi in wastewater remediation, are mentioned.
... Twin studies by Cajthaml et al. [54] and Bhatt et al. [55] concluded that composting is "substantially more efficient in removing all PAHs, including higher molecular weight ones, than fungal treatment". However, the two studies differed in some important respects, raising the question of whether they are indeed comparable. ...
... The compost chamber dimensions were 1.3 × 1.35 × 2.5 m, with aeration tubes. Bhatt et al. [55] layered the same contaminated soil with straw colonized with mycelium in one-liter Erlenmeyer flasks. The Cajthaml treatment was large enough to achieve a thermogenic effect, as opposed to Bhatt's smaller treatment. ...
Pleurotus ostreatus, a gilled basidiomycete, has previously been shown to biodegrade petroleum using extracellular enzymes. However, few studies have tested petroleum biodegradation by fungi, known as mycoremediation, in cold temperatures. I conducted mesocosm studies to assess the potential from mycoremediation of diesel-contaminated soil collected from interior Alaska with a cultivated strain of P. ostreatus var. columbinus at 4ºC, 10ºC, and 25ºC. In soil, both uninoculated and inoculated with P. columbinus, diesel range
organics (DRO) decreased by 22-28% (p=0.455), 41-55% (p=0.236), and 91-92% (p=0.735) at the three temperatures, respectively. The differences in DRO loss between uninoculated and inoculated mesocosms at each temperature were not statistically significant, most likely due to high soil heterogeneity. However, DRO loss was greater as temperature increased, and was significantly different between the temperatures evaluated. These results indicate that
temperature is a more important factor controlling DRO loss than substrate or inoculation with P. columbinus. Inoculation may enhance DRO loss at medium temperatures, but inoculation does not appear to enhance DRO loss at the highest and lowest temperatures in this study. The results also suggest that manipulating the temperature of remediation sites may be more important than inoculating with Pleurotus, and that inoculation might not be needed at sites where temperature can be increased.
... Irpex lacteus (Fr.) Fr. was reported by various studies to degrade PAH, e.g., Bhatt et al., [98] Cajthaml et al., [99] Novotn y et al., [100] Matsubara et al., [82] Leonardi et al. [101] Laetiporus sulphureus degraded phenanthrene as reported by Sack et al. [51] Matheus et al. [102] reported the degradation of hexachlorobenzol by a Lentinus species. Lenzites betulina (L.) Fr. was reported to degrade PCP by Tortella et al. [88] Phanerochaete chrysosporium Burds. is perhaps the most widely used basidiomycete species for hydrocarbon bioremediation. ...
... Pleurotus ostreatus (Jacq.) P. Kumm. is another widely used basidiomycete for bioremediation: Eggen [113] reported the use of spent mushroom compost to degrade several PAH while Bhatt et al. [98] and Novotn y et al. [105] reported similar results from contaminated soils. PAH degradation was also shown by Matsubara et al., [82] Leonardi et al. [101] and by Vyas et al. [91] for anthracene, while d'Annibale et al. [85,86] observed the degradation of aromatic hydrocarbons by Pleurotus sp. ...
The literature on hydrocarbon remediation with basidiomycetes was reviewed. Two ecological groups are considered for bioremediation, the saprotrophic basidiomycetes (white-rot and brown-rot fungi) and the ectomycorrhizal basidiomycetes. A remarkable capacity of basidiomycetes for in vitro degradation of simple and recalcitrant hydrocarbons, such as PAH, persistent organic pollutants (POPs), halogenated HC, aromatic HC and phenols, explosives and dyes was reported for many species. However, there is a need for more studies on the practical feasibility of field applications with basidiomycetes.
... Rhodotorula mulcilaginosa exhibited 35.85% degradation capacity of hydrocarbons in waste engine oil from petrol driven vehicle among the fungi used in this study. This was in accordance withBhatt et al. (2002), who reported that Rhodotorula sp. contributed to effective degradation of low molecular weight PAHs and other hydrocarbon components in crude oil. ...
The isolation and identification of hydrocarbon degrading bacteria and fungi from waste engine oil contaminated soil obtained from Mechanical Village, Uyo, Akwa Ibom State, their distribution frequency and hydrocarbon degradation capacity were investigated using standard method. The results revealed that Bacillus myocoides, Staphylococcus aureus, Listeria murrayi, Actinomycete viscosus, Clostridium sporogenes, Bacillus licheniformis, Corynebacterium ulcerans and Clostridium histolyticum were bacteria identified. Fungi identified were Fusarium oxysporum, Cryptococcus terreus, Penicillium notatum, Aspergillus fumigatus, Rhizopus stolonifer, Rhizopus oryzae and Rhodotorula mulcilaginosa. Their distribution frequency were B. myocoides (27.9 %), S. aureus (8.1 %), L. murrayi (9.9 %), A. viscosus (11.7 %), C. sporogenes (16.2 %), B. licheniformis (7.2%), C. ulcerans (12.6 %) and C. histolyticum (6.3 %) for bacteria. For the fungi, F. oxysporum (15.3 %), C. terreus (4.1%), P. notatum (20.4 %), A. fumigatus (11.2 %), R. stolonifer (10.2 %), R. oryzae (24.5%) and R. mulcilaginosa (14.3%). The efficiency of the microbial isolates to degrade waste engine oil from petrol and diesel driven vehicles as their major source of energy were found to vary among the microorganisms. C. sporogenes degraded waste engine oil from petrol driven vehicle with the highest efficiency (38.09%), whereas S. aureus demonstrated the least efficiency (19.28 %). C. histolyticum utilized waste oil from diesel vehicle with the highest efficiency (35.00%), while C. ulcerans was the least (17.31%). Among the fungi isolates, R. mulcilaginosa showed most degradation potential for spent oil from petrol driven vehicle (34.85 %) whereas C. terreus was the least (20.00 %). A. fumigatus exhibited highest degradation capacity for spent oil from diesel driven vehicle (29.73 %) while R. oryzae demonstrated the least potential (20.76 %). These results implied that microbial consortium could best be used for remediation of hydrocarbon contaminated soil.
... Human-caused activities such as coal mining, municipal runoff, transportation, and storage (Varjani, 2017). Pleurotus ostreatus and Irpex lacteus degrade polyaromatic hydrocarbons from contaminated industrial soil (Bhatt et al., 2002). ...
Integrating fungi into fuel cell systems presents a promising opportunity to address environmental pollution while simultaneously generating energy. This review explores the innovative concept of constructing wetlands as fuel cells for pollutant degradation, offering a practical and eco-friendly solution to pollution challenges. Fungi possess unique capabilities in producing power, fuel, and electricity through metabolic processes, drawing significant interest for applications in remediation and degradation. Limited data exist on fungi’s ability to generate electricity during catalytic reactions involving various enzymes, especially while remediating pollutants. Certain species, such as Trametes versicolor, Ganoderma lucidum, Galactomyces reessii, Aspergillus spp., Kluyveromyce smarxianus, and Hansenula anomala, have been reported to generate electricity at 1200 mW/m3, 207 mW/m2, 1,163 mW/m3, 438 mW/m3, 850,000 mW/m3, and 2,900 mW/m3, respectively. Despite the eco-friendly potential compared to conventional methods, fungi’s role remains largely unexplored. This review delves into fungi’s exceptional potential as fuel cell catalysts, serving as anodic or cathodic agents to mitigate land, air, and water pollutants while simultaneously producing fuel and power. Applications cover a wide range of tasks, and the innovative concept of wetlands designed as fuel cells for pollutant degradation is discussed. Cost-effectiveness may vary depending on specific contexts and applications. Fungal fuel cells (FFCs) offer a versatile and innovative solution to global challenges, addressing the increasing demand for alternative bioenergy production amid population growth and expanding industrial activities. The mechanistic approach of fungal enzymes via microbial combinations and electrochemical fungal systems facilitates the oxidation of organic substrates, oxygen reduction, and ion exchange membrane orchestration of essential reactions. Fungal laccase plays a crucial role in pollutant removal and monitoring environmental contaminants. Fungal consortiums show remarkable potential in fine-tuning FFC performance, impacting both power generation and pollutant degradation. Beyond energy generation, fungal cells effectively remove pollutants. Overall, FFCs present a promising avenue to address energy needs and mitigate pollutants simultaneously.
... Petroleum products and PAHs, widely used in various industries, have the potential to pollute the environment, water bodies, and seas, with harmful effects on both wildlife and human health due to their carcinogenic properties 2,37 . Mycoremediation has emerged as a promising approach to biodegrade various pollutants in natural ecosystems 38 . Tremendous efforts have been made to isolate organisms, such as fungal www.nature.com/scientificreports/ ...
A total of 265 fungal individuals were isolated from soils exposed to heavy oil spills in the Yadavaran oil field in Iran to discover indigenous fungal species with a high potential to biodegrade petroleum hydrocarbon pollutants. Morphological and molecular identification of obtained fungal species led to their assignment into 16 genera and 25 species. Alternaria spp. (78%), Fusarium spp. (5%), and Cladosporium spp. (4%) were the most common genera, along with Penicillium spp., Neocamarosporium spp., Epicoccum sp., Kotlabaea sp., Aspergillus sp., Mortierella sp., and Pleurotus sp. A preliminary screening using the DCPIP indicator revealed that approximately 35% of isolates from Alternaria, Epicoccum, Neocamarosporium, Cladosporium, Fusarium, Stachybotrys, Penicillium, and Stemphylium demonstrated promising tolerance to crude oil. The best-performing isolates (12 fungal individuals) were further investigated for their capacity to mineralize a mixture of four polycyclic aromatic hydrocarbons (PAH) for 47 days, quantified by GC–MS. Eventually, two top-performing isolates, namely 5c-12 (Alternaria tenuissima) and 3b-1 (Epicoccum nigrum), were applied to petroleum-contaminated soil. The GC–MS analysis showed that 60 days after inoculation, these isolates successfully degraded more than 70% of the long-chain hydrocarbons in the soil, including C8-C16 n-alkanes, C36 n-alkane, and Pristane. This study introduces two fungal species (5c-12 and 3b-1) with high potential for biodegrading petroleum compounds and PAHs, offering promising prospects for the decontamination of oil-contaminated soil.
... Fungi degrade pesticides, dyes, polychlorinated biphenyls, hydrocarbons, and phenolic and chlorinated compounds with the use of different enzymes (laccases, manganese peroxidase, and lignin peroxidases) [96]. Irpex lacteus and Pleurotus ostreatus degrade PAH from contaminated industrial soil [97]. Many fungi (Fusarium oxysporum, Mucor alternans, Tricoderma viride, and Phanerochaete chrysosporium) can degrade DDT. ...
Pure water, i.e., a sign of life, continuously circulates and is contaminated by different discharges. This emerging environmental problem has been attracting the attention of scientists searching for methods for the treatment of wastewater contaminated by multiple recalcitrant compounds. Various physical and chemical methods are used to degrade contaminants from water bodies. Traditional methods have certain limitations and complexities for bioenergy production, which motivates the search for new ways of sustainable bioenergy production and wastewater treatment. Biological strategies have opened new avenues to the treatment of wastewater using oxidoreductase enzymes for the degradation of pollutants. Fungal-based fuel cells (FFCs), with their catalysts, have gained considerable attention among scientists worldwide. They are a new, ecofriendly, and alternative approach to nonchemical methods due to easy handling. FFCs are efficiently used in wastewater treatment and the production of electricity for power generation. This article also highlights the construction of fungal catalytic cells and the enzymatic performance of different fungal species in energy production and the treatment of wastewater.
... Microorganisms with a high degrading potential for polycyclic aromatic hydrocarbons (PAHs) are critical for effective PAH contaminated remediation. A white rot fungus (Phanerochaete chrysosporium) has been shown to degrade PAHs extensively (Zheng and Obbard 2000;Bhatt et al. 2002). ...
Main conclusion
EF have been explored for its beneficial impact on environment and for its commercial applications. It has proved its worth in these sectors and showed an impact on biological properties of plants by producing various bioactive molecules and enzymes.
Abstract
Endophytes are plant mutualists that live asymptomatically within plant tissues and exist in almost every plant species. Endophytic fungi benefit from the host plant nutrition, and the host plant gains improved competitive abilities and tolerance against pathogens, herbivores, and various abiotic stresses. Endophytic fungi are one of the most inventive classes which produce secondary metabolites and play a crucial role in human health and other biotic aspects. This review is focused on systematic study on the biodiversity of endophytic fungi in plants, and their role in enhancing various properties of plants such as antimicrobial, antimycobacterial, antioxidant, cytotoxic, anticancer, and biological activity of secondary metabolites produced by various fungal endophytes in host plants reported from 1994 to 2021. This review emphasizes the endophytic fungal population shaped by host genotype, environment, and endophytic fungi genotype affecting host plant. The impact of endophytic fungi has been discussed in detail which influences the commercial properties of plants. Endophytes also have an influence on plant productivity by increasing parameters such as nutrient recycling and phytostimulation. Studies focusing on mechanisms that regulate attenuation of secondary metabolite production in EF would provide much needed impetus on ensuring continued production of bioactive molecules from a indubitable source. If this knowledge is further extensively explored regarding fungal endophytes in plants for production of potential phytochemicals, then it will help in exploring a keen area of interest for pharmacognosy.
... The antagonistic interactions between soil bacteria and fungi may be caused by competition for an available carbon source [11]. In the degradation of some pollutants, fungi act synergistically with bacteria [7,12,13]. In such a case, the fungal and bacterial degradation pathways may complement each other. ...
Bacterial-fungal interactions are important in the functioning of natural ecosystems. We examined possible synergistic or antagonistic effects during the degradation of polycyclic aromatic hydrocarbons (PAHs) by a fungal–bacterial co-culture. Bacteria and fungi were grown in a liquid nutrient medium supplemented with PAH substrates. The degradation of PAHs and the identification of metabolites were checked by HPLC. Enzyme activities were spectrophotometrically measured with test substrates. Compared to monocultures, the co-culture yielded higher mycelium dry weights and higher numbers of bacterial colony-forming units (CFUs). Both organisms and their co-culture transformed three- and four-ring PAHs into the corresponding quinones. The degradation of PAHs was accompanied by the production of fungal extracellular laccase and versatile peroxidase, whose activities were higher in the co-culture than they were in the monocultures. The presence of exogenous indole-3-acetic acid (IAA) boosted PAH degradation and enzyme production. The xylotrophic basidiomycete Pleurotus ostreatus Florida and the plant-growth-promoting rhizobacterium Azospirillum brasilense exerted a positive mutual effect, including increases in mycelium dry weight, number of CFUs, degradation of PAHs, and production of fungal extracellular enzymes. IAA may be a factor in the interactions of P. ostreatus Florida with A. brasilense.
... Three hundred grams of the artificial soil was put in a sealed glass enclosure and spiked with methanol solution (90 mL) containing 1.12 mg of each PAH. PAHs concentrations in the natural soil are generally lower than spiked in this study, but it can be much higher according to concentrations of polluted sites in literature (Bhatt et al. 2002;Eom et al. 2007). PAHs-spiked soil samples undergo exhaustive handhomogenization. ...
Sorption by soil organic matter (SOM) is considered the most important process affecting the bioavailability of hydrophobic organic chemicals (HOCs) in soils. The sorption capacity of SOM for HOCs is affected by many environmental factors. In this study, we investigated the effects of soil pH on the sorption capacity of SOM using batch sorption experiments. The soil organic carbon-water partition coefficients (KOC) of six selected polycyclic aromatic hydrocarbons (PAHs) were measured in artificial soil under various soil pH and water saturation conditions. Passive sampling was used for measurement of KOC with polydimethylsiloxane as sampling material. Regardless of soil pH, KOC increased with increasing soil water saturation for low molecular weight PAHs. On the contrary, KOC decreased with increasing soil water saturation for high molecular weight PAHs. Despite some fluctuations, KOC tended to decrease with increasing soil pH at all water saturations. This indicates that earlier studies on the effects of soil pH on KOC in saturated conditions could be extended to unsaturated soils. These KOC tendencies were reproduced in three different natural soils, suggesting that the effects of water saturation and soil pH might be generalized, at least for PAHs. The sorption capacity of SOM was found to be resilient under dynamic soil pH conditions. The range of sorption capacity of SOM under dynamic soil pH conditions can be used for adjusting the effects of soil pH.
... Fungi have efficient degradation ability, as it has been reported on several occasions when it degrades different types of materials such as plastic and leather, among others. For instance, Irpex lacteus and Pleurotus ostreatus reduced PAH from contaminated industrial soil (Bhatt et al. 2002). It is important to highlight that fungi also contribute to the elimination of pesticides, dyes, hydrocarbons, polychlorinated biphenyls, and chlorinated and phenolic compounds through the use of different enzymes produced by them, such as laccases (Bhattacharya et al. 2012). ...
Pollution represents a serious risk to living forms once it can cause from acute intoxication to death. In order to avoid the damage or restrict it, if it is not possible to eliminate it, it is necessary to develop remediation strategies. These different strategies offer a large array of options available to be used in an optimized way to remediate different kinds of environs and of pollutant or pollutants (organic and/or inorganic) present. Remediation protocols can use living organisms (biological remediation) or not (physicochemical remediation). The former group is the focus of this chapter that explores biotechnologies to restore contaminated environs and contribute to the achievement of sustained development. The use of plants, microorganisms, biochars, nanomaterials, and also the genetic manipulation of living beings are discussed as tools to develop efficient and safe protocols to try to repair the damages anthropic action caused and still causes over ecosystems.
... Menurut Paul Stamets (2005), yang bekerja sama dengan Laboratorium Battele Pasifi c Nortwest di Sequim, Washington, menunjukkan bahwa P ostreatus memproduksi enzim yang dapat memecah dan mmenetralkan beberapa bahan industri yang bersifat racun yang membandel yang ahirnya dapat berperanan menuju perbaikan habitat dan lingkungan (Thomas et al, 1999). Aktivitas ini kemudian telah dikonfi rmasi para peneliti (periset) dari benua Eropah, termasuk Bhatt et al (2002), Cajthaml et al (2002), dan Eggen dan Sasek (2002) yang juga menemukan bahwa "spent compost" atau "spent mushroom" bekerja lebih baik untuk memecah bahan toksin dari pada yang segar, bibit kultur yang murni. Hal ini merupakan penemuan yang sangat luas penerapannya yang implikasinya dapat berdampak sebagai nilai tambah penggunaaan dan pemanfaatan limbah substrat (media) yang berasal dari perkebunan budidaya jamur tiram (oyster mushroom). ...
Oyster mushroom as a source of nutritious food and medicinal source is known since Chow Dynasti in China.However, its potential for environmental rehabilitation as known as mycorestoration is being investigatedby Paul Stamets in 2005. If oyster mushroom can control the world that could support from the smallestthings as food becoming bigger roles in the future, such as poverty eradication, improving soil fertility, andrehabilitating environmental condition, degrading toxic pollutant, protecting human health from diseases,and helping community to integrate complex waste recycle, so oyster mushroom is emerging as a strongcommodity to improve our welfare. This paper is trying to promote the role of oyster mushroom to provideits strength for both as nutrious food and medicinal source, and also for its ability to restore degraded soilfertility, and improving to remediate contaminated soils. In line with those things, and the most importantfor the people of Indonesia is trying to help increase their income through promoting mushroom cultivation,because Indonesia has a hugh potential for lignocelluslose materials and agricultural waste, and then itsspent mushroom can be used for animal feed and soil amelioration and soil remediation. Based on theStamet investigation this spent mushroom can be used for environmental rehabilitation of toxic pollutantssuch as PCB (Polychlorinated Biphenils), PAH (Polycyclic Aromatic Hydrocarbon), Azo dyes, and otherpersistent organic pollutants (POP’s).Key words: Oyster mushroom, Pleurotus ostreatus, mycorestoration, soil remediation, environmentalrehabilitation.
... There have been certain constraints with the process also, as the research has shown that mushroom species like P. ostreatus and P. chrysosoporium have emerged as model systems for studying bioremediation. But, still the process know-how is still Bumpus et al. (1985), Aitken and Irvine (1989), Barr and Aust (1994), Nigam et al. (1995), Sasek and Cajthaml (2005), Leonardi et al. (2007), Adenipekun and Lawal (2012), and Thakur (2014) 2 Lentinus edodes Degrade pentachlorophenol (PCP) Adenipekun and Lawal (2012) and Thakur (2014) Bhatt et al. (2002) and Adenipekun and Lawal (2012) a mystery on how this white-rot fungus removes pollutants. Major constraint of this process was Phanerochaete chrysosporium as the major work on mycoremediation is on this fungus only. ...
The rising demand for environmentally friendly, organic, and sustainable agricultural practices is driving the application on the use of beneficial biological products. Sustainability has become an integral component of the agriculture system. The use of fungi in agriculture sector is potentially useful for improved plant health and growth, water uptake, nutrient availability, stress tolerance, and biocontrol. Fungal species served as a very important biological tool in sustainable agricultural ecosystem with the process of mycoremediation, mycocontrol—mycoherbicides, mycoinsecticides, and as mycorrhiza fungi. Examples of fungi used as mycoremediators are—Pleurotus ostreatus, Rhizopus arrhizus, Phanerochaete chrysosporium, P. sordid, Trametes hirsute, T. versicolor, Lentinus edodes, and L. tigrinus. The fungi plays a pivotal role in the process of mycoremediation, mycocontrol, mycoherbicides, mycoinsecticides, as mycorrhizal fungi and have potential role for attaining sustainable agricultural systems. The chapter aims to study the role of fungi and ways to exploits their potential to remediate polluted soil and build a sustainable agriculture system.
... In addition to the use of bacteria, the use of white-rot fungi has been proposed to remedy sediments contaminated with PAHs and OCs (Bhatt et al. 2002, Cajthaml et al. 2008). These organisms can degrade POPs in very low concentrations and can access less bioavailable pollutants, since the induction of enzymes is independent of the presence of the pollutant (Canet et al. 1999). ...
Remediation of marine systems, which could be polluted by both organic and inorganic contaminants, is a complex process. Traditional remediation strategies include chemical, physico-chemical and thermal techniques, which are still widely used. However, biological techniques have begun to be applied, as they are eco-friendly and low cost alternatives. Biological remediation includes bioremediation and phytoremediation, which are defined as the use of microorganisms and plants, respectively, to remediate polluted sites.
This chapter first describes briefly the physico-chemical factors that can affect bioremediation and phytoremediation and, in the case of bioremediation, the microorganisms that could be involved. Then, the different bioremediation (bioaugmentation, biostimulation, bioventing, bioleaching, etc.) and phytoremediation (phytoextraction, phytostabiliazation, phytovolatilization, etc.) strategies are defined. Finally, emphasis is placed on the biological remediation of marine systems, both in seawater and in sediments. This part is divided into inorganic (namely metals) and organic (oil spills and persistent organic pollutants) pollutants, discussing the different bioremediation and phytoremediation strategies that are applied or could be applied in marine systems. Combinations of techniques and novel approaches including genetic engineering are also considered.
... One such alternative involves mycoremediation, a form of bioremediation that uses mycelia, the underground body structure of fungi, to remove contaminants. Mycoremediation is a tool that has been used relatively recently for soil pollutant removal from industrial settings such as hydrocarbons, heavy metals like lead and arsenic (Thomas et al. 1998;Bhatt et al. 2002;Da Silva et al. 2003;Giubilei et al. 2009;Olorunfemi et al. 2015;Singh et al. 2015;Anderson and Juday 2016;Kapahi and Sachdeva 2017;Treu and Falandysz 2017;Hassan et al. 2019), and PAHs (Šašek and Cajthaml 2005;Leonardi et al. 2008;Giubilei et al. 2009;Bhattacharya et al. 2012;Anasonye et al. 2018). Some fungi also exhibit antimicrobial properties towards human pathogens such as Staphylococcus aureus (Stamets 2005). ...
Wastewater pollution results in detrimental effects on ecosystems and poses human health hazards. As the human population and urbanization rates increase, so do abiotic and biotic contaminants such as Escherichia coli within natural waterways. For example, the Chicago River has been degraded by contaminants and untreated sewage from city occupants since the late 1700s. Surprisingly, water treatment of the Chicago River has not met EPA freshwater river standards for some time, creating a need for remediation alternatives. Such an alternative is mycoremediation, where fungi are used to degrade and remove water contaminants. To explore this alternative for bioremediation of contaminated waterways, this two-part study focused on the feasibility and time efficiency of mycoremediation of polluted waters through mycofiltration. In the lab-based experiment, known amounts of E. coli–inoculated water were processed through organic wheat straw with mycelia of Pleurotus ostreatus (oyster mushroom) to assess if these fungi were capable of E. coli removal and at what rates. The second part of the study replicated the lab-based experiment with water samples from the Chicago River. Results showed that mycelia treatments were able to remove significant amounts of E. coli in lab- and field-sampling-based settings (99.25% and 99.74% over 96 h respectively), and did so at higher rates within the initial 48 h. With a substantial E. coli reduction by fungal mycelia from initial colony counts over 96 h, our study demonstrated that mycoremediation may be a feasible and possible option for natural contaminant remediation.
... 2,70 The actively growing mushrooms substrates may be pre-developed to a level where mycelia are actively sprouting before inoculation of soils, or spawns may be inoculated directly on substrates layered on soils. 76, 87 Adenipekun 70 described a procedure whereby 400 g of soils was articially contaminated with 0-30% of spent cutting uid-SCF and fresh cutting uids-FCF and placed in sterile 350 ml bottles. 80 g of moistened rice straw were then laid on these soils, and aer sterilization and cooling, 10 g of the actively growing mushrooms spawns were inoculated on the samples. ...
Mycoremediation, an aspect of bioremediation, has been investigated for some decades. However, there seems to be little progress on its commercial application to petroleum-contaminated soils despite some promising outcomes. In this review, mycoremediation is examined to identify development, limitations and perspectives for its optimal utilization on petroleum-contaminated soils. Mycoremediation agents and substrates that have been used for the treatment of petroleum contaminated soils have been identified, application methods discussed, recent advances highlighted and limitations for its applications accentuated. Possible solutions to the challenges in applying mycoremediation to petroleum-contaminated soils have also been discussed. From this review, we conclude that for optimal utilization of mycoremediation of petroleum-contaminated soils, ideal environmental, edaphic and climatic factors of a typical contaminated site must be incorporated into the approach from first principles. Development of application procedures that can easily translate laboratory results to field applications is also required.
... It was reported that PAH can be metabolized by microorganisms. Some researchers had investigated the white-rot fungal cultures are potential to degrade PAH [20,147]. Various groups of enzymes (manganese peroxidase, laccases, and lignin peroxidises) are biosynthesized by different groups of fungus, which can enhance the degradation rate of dyes, pesticides, polychlorinated biphenyls, chlorinated and phenolic compounds, hydrocarbons, etc. [103,147]. ...
The world is witnessing various pollutants in the environment since the last few decades that threaten human life. The biological responses to various pollutants show variations as the living system behaves differently in their sensitivities to the same types of pollutants. The relative response and activity depend upon the duration of exposure to the specific pollutant. It is impossible to stop various activities leading to environmental pollution; however, pollutants can be eliminated from the environment using the microorganisms. Application of biological processes can be executed in order to get rid of toxic pollutants through their biodegradation. The pollutants like hydrocarbons, heavy metals, chlorinated hydrocarbons, nitro-aromatic compounds, non-chlorinated herbicides and pesticides, organophosphates, radionuclides can lead to serious health and environmental problems. The main objective of this paper is to evaluate the effects of pollutants on the living beings and environment, microbial responses to pollution, and distribution of various biodegrading microorganisms in the environment. Profiling of biodegrading microorganisms, microbial biosensor to detect environmental pollution, and strain improvement through genetic manipulation to enhance the biodegradation process have been discussed in detail.
... The half-lives of chlorpyrifos in fungi treated soil and on B. chinensis L. were markedly reduced under both greenhouse and field conditions. Bhatt et al. (2002) demonstrated the potential of white rot fungi, including Irpex lacteus and P. ostreatus, for the treatment of polyaromatic hydrocarbon (PAH) contaminated industrial soils. The tested fungi were able to degrade soil contaminated with seven aromatic compounds containing, namely fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, and benzo[a]anthracene. ...
... Microorganisms having a high capacity to degrade PAHs are important for the adequate remediation of PAH contamination. White rot fungus Phanerochaete chrysosporium has been reported to extensively degrade PAHs (Bhatt et al. 2002;Šašek et al. 2003;Zheng and Obbard 2000). The achievement of bioremediation depends on certain factors, such as the physicochemical and biological properties of the soil (Alexander 1994), contaminant types and their concentrations (Providenti et al. 1993), the ability of particular microorganisms to grow in a given soil and to degrade the target contaminants (Pointing 2001), and the bioavailability of contaminants (Semple et al. 2003). ...
... PAH, is degraded by Irpex lacteus and Pleurotus ostreatus from contaminated industrial soil. It was found that the white-rot fungal cultures are capable of not only degrading PAH but also remove the different PAHs (Bhatt et al., 2002). Fungi are also assists in the degradation of pesticides, dyes, hydrocarbons, polychlorinated biphenyls, chlorinated and phenolic compounds by the use of different enzymes produced by them such as laccases, manganese peroxidase (MnP) and lignin peroxidises (LiP) (Bhattacharya et al., 2012). ...
This paper presents a comprehensive review of the current state of research activities on the application of biodegradation/bioremediation for removing persistent organic pollutants (POPs) such as pesticides, PCBs, PAHs and PPCPs from wastewater. Several potential enzymes have been reported from various microorganisms, which breakdown the complex compounds through biodegradation, biostimulation or bioaugmentation process. Various microorganisms, harbouring numerous plasmids and catabolic genes, acclimatize to these environmentally unfavourable conditions by gene duplication, mutational drift, hypermutation, and recombination. Genetic aspects of some major POP catabolic genes such as biphenyl dioxygenase (bph), hydroxylation, phosphotriesterases and oxygenase etc. assist in degradation organic pollutants. However with the advent of technological advancements in genetic engineering is being considered the possibility for the role of genetically modified organisms, metagenomics and metabolomics is being considered to develop low cost, effective and reliable method for detection, determination and removal of ultra-trace concentration of POPs. In addition, development in microbial fuel cell, nano-materials, biofilms and constructed wetlands augments the biodegradation process. Therefore, this review highlights the effect of POPs on the environment, health hazards, microbial degradation and its mechanism along with brief study of advanced oxidation process for wastewater treatment.
... These enzymes are believed to enhance the ability of white-rot fungi in the breaking down of lignin in plant biomass and obtain a better access to the cellulose than by bacteria [7]. Therefore, white-rot fungi are good degraders of aromatic and polycyclic aromatic compounds in different environments, including soil [9][10][11]. For white-rot fungi to degrade these pollutants, it requires a substrate that will support its growth on such pollutants. ...
... lacteus were: fluorene (41 and 67%), phenanthrene (20 and 56%), anthracene (29 and 49%), fluoranthene (29 and 57%), pyrene (24 and 42%), chrysene (16 and 32%) and benzo[a]anthracene (13 and 20%). In the same two industrial soils P.ostreatus degraded the PAH with respective removal figures of fluorene (26 and 35%), phenanthrene (0 and 20%), anthracene (19 and 53%), fluoranthene (29 and 31%), pyrene (22 and 42%), chrysene (0 and 42%) and benzo[a]anthracene (0 and 13%) 30 . After 192 h of incubation, Cyclothyrium sp. was able to degrade simultaneously 70, 74, 59 and 38% of phenanthrene, pyrene, anthracene and benzo[a]pyrene 31 . ...
A wide number of fungal species have shown incredible abilities to degrade a growing list of persistent and toxic industrial waste products and chemical contaminants to less toxic form or non-toxic form. Mycelium reduces toxins by different enzymatic mechanism to restore the natural flora and fauna. White rot fungi has successfully been utilized in degradation of environmental pollutant like polyaromatic compounds, pesticides etc. The present review gives a insights on degradation aspects of heavy metals, PAH especially using different fungal species. White rot fungi has potential to degrade contaminants using wide range of enzymes. Mycoremediation is promising alternative to replace or supplement present treatment processes.
... With the adaptability of fungi, mycoremediation could be an alternate way to ensure greater cleaning efficiency during the winter when the necessary growth conditions for plantbased systems are lacking. Remediation using fungi, especially mycoremediation of soils, has been demonstrated in several cases (Bhatt et al. 2002;Singh 2006;Giubilei et al. 2009;Molla & Fakhru'l-Razi 2012). Therefore, mycoremediation can be eligible to improve and complement phytoremediation efficiency. ...
The increasing anthropogenic pollution of aquatic environments and fresh water scarcity worldwide have prompted the development of low-cost and effective water treatment alternatives. One example of a highly released anthropogenic xenobiotics is acetaminophen (APAP), which has been detected in surface waters at concentrations as high as 5 μg/L. To date, traditional water treatment plants were unable to remove all pharmaceutical xenobiotics and as in the case with APAP, the breakdown products are toxic. Phytoremediation has proved to remove xenobiotics efficiently producing no toxic breakdown products, however, they are often restrained in their application range. Therefore, it was necessary to find alternate remediation tools to extend and complement the application ranges of existing bioremediation techniques. With the success of mycoremediation as well as the adaptability of fungi, Mucor hiemalis was investigated in terms of its APAP uptake capabilities. The investigation included the examination of concentration- and time-dependent uptake studies to examine the effects of each of these parameters independently. Additionally, the extracellular peroxidase activity of M. hiemalis was measured with exposure to APAP to evaluate possible breakdown and the antioxidative stress enzymes, catalase, glutathione peroxidase and glutathione reductase, were assayed to investigate whether APAP caused oxidative stress. The results showed that M. hiemalis was able to internalize between 1 and 2 μg APAP per g dried fungal biomass when exposed to 5, 10, 50 and 100 ng/ml APAP for 24 to 48 h, but not beyond this time frame. Further, exposure to APAP did not result in elevated extracellular peroxidase activity or oxidative stress. The findings led to the conclusion that M. hiemalis could be integrated in bioremediation systems, for short-term degradation at low concentrations of APAP with effective management.
Rehabilitation of mine tailings in the country is a challenge to improve soil quality and increase biodiversity particularly on copper-rich soil from pine forest in Mankayan Mountain Province. It is hypothesized that specific mycorrhizal fungi coexist with pines where undergrowth forest plants can be sourced of planting materials with inoculation of local mycorrhizas. This is the purpose of the study to investigate nursery response of an undergrowth species where soil was amended with mycorrhizas. Initially, transects were first established across benguet pine forest in mountainous watershed ecosystem to assess diversity of undergrowth following quadrat sampling technique. Ectomycorrhizal fungi were collected beneath for descriptive characterization while endomycorrhizas were isolated through wet sieving technique to prepare the inoculant. Mine soil was prepared for chemical analysis and sterilized as potting medium for seed box and pot experiments. Calophyllum inophyllum L. was used to represent undergrowth and determined nursery response to mined-out soils inoculated with mycorrhizal treatments (MykoVam, natural soil) using growth, survival, and association as parameters. Diversity analysis revealed 32 families of undergrowth forest plants under pine forest represented by genus Calophyllum. Five kinds of basidiomycetous ectomycorrhizas and three genera of endomycorrhizas were morphologically described, identified and served as inoculant. Nursery growth of C. inophyllum L. (Bitaog) to a mined-out soil amended with MykoVam and natural soil yielded the highest survival rate that significantly improved root growth after 50 days (p < 0.01206). Shoot length significantly increased after 50 days (p < 003123) though no significant difference was observed across soil treatments. Sampled fine roots of C. inophyllum also showed formation of mycorrhizas indicating association. Raising indigenous trees in copper soil with mycorrhizas can improve growth and survival in nursery condition which are important before outplanting seedlings during mining rehabilitation.
Mycoremediation is a technique that transmutes toxic, recalcitrant pollutants into environmentally safe products by organic treatments. It is a green method for cleaning up polluted sites. Because of a breakthrough in technology, exceedingly harmful contaminants are persistently released into the environment via industries. Polycyclic aromatic hydrocarbons (PAHs), heavy metals, polychlorinated, and pharmaceutical compounds (PhC) are mutagenic. They are freed by petroleum refineries, textile mills, and vehicle exhaust. Human exposure has risen because of their rampant use in certain industrial, agricultural, and domestic fields. Recently, there has been a growing ecological and global public health concern accompanying environmental contamination. The traditional methods applied to remove them pose risk to the ecosystem. Remediation of polluted sites has become a center of attention within society because of accelerating public awareness. The theory of mycoremediation has come up from the chief role of fungi within the ecosystem, which is to decompose. Nonetheless, the dominating biomass in soil are fungi, which still have not been exploited aptly for mycoremediation. Microfungi and macrofungi both contribute to the feasibility of mycoremediation. Their wealthy enzyme compositions assist the process. The objective of this chapter is to review the role of contaminants on the environment as well as to focus on the part of fungi in eliminating them. We have discussed in detail the various works and the contemporary advancements; futuristic omics approaches that are in the midst of progress.
Aquatic fungi are a diverse group of eukaryotic creatures. Since 1944, marine fungi have been widely investigated, particularly wood-inhabiting fungi. Aquatic fungi have recently become a focus of research, particularly for bioprospecting. They can produce several novel molecules with bioactive capabilities, including enzymes, antibiotics, anticancer properties, and bioremediation. Certain aquatic fungi play an essential role in the decomposing of xenobiotics and also in nutrient cycling. Aquatic fungi can treat organic or metal contaminants in surface soils, concentrated or trace organic pollutants in water streams, remove metals from water streams, volatile organic chemicals from air streams, and remove organic impurities. The polysaccharide- and polyphenol-degrading enzymes found in some aquatic fungi are more diverse and effective than those found in terrestrial fungi, indicating them to play an important role in biotransformation. In this chapter, we have tried to outline fungi’s metabolic and ecological characteristics that make them suitable for use in the bioremediation of pollutants, bioprospecting- for the search of new biologically active compounds, and in the biotransformation of toxic wastes and contaminants.
Environmental stresses adversely affect plant growth and have a major impact on agricultural production worldwide. Different strategies, namely, molecular, physiological, and agronomical methods were employed to confer stress tolerance to plants, plant–microbe associations being one of the key explored areas. Among plant-associated fungal communities, fungal endophyte and arbuscular mycorrhizal fungi comprise the beneficial fungi that improve plant growth and productivity. A better understanding of the functional dynamics and how the fungal communities confer beneficial traits to plants would be an ideal platform for enhancing crop productivity and a more sustainable agriculture. Highlighting the emerging importance of plant-associated fungal communities and their multifaceted beneficial role in the ecosystem, this chapter extensively discusses the functional dynamics of the fungal communities in conferring stress tolerance and promoting plant growth. With a brief overview of the composition of fungal microbiomes and their mutualistic association with higher plants, a better understanding of how these microbial communities confer beneficial traits to plants is essential to increase crop productivity and sustainable agriculture.
Aquatic chemistry has become a rewarding and substantial area of research that is attracting many scientists. Its literature has changed from a compilation of composition tables to studies of chemical reactions that take place within aquatic environments. Given that the rivers deliver to the world’s oceans most of their dissolved and particulate components, the interactions of these two sets of waters determine the vitality of our coastal waters. This chapter not only provides an introduction to the dynamics of aquatic chemicals, but also identifies materials that endanger marine and fluvial resources. The information presented here will be of great value to environmental scientists dedicated to maintaining renewable hydrosphere resources. As the size of the world population will increase in the near future and the uses of materials and energy show parallel increases, rivers and oceans should be considered as a resource to accept some of society’s waste. The capacity of these waters and the sediments to accommodate the waste must be evaluated continuously. The information presented in this chapter is based on the review and evaluation of scientific publications and technical reports from various sources.
The sorption capacity of soil organic matter (SOM) for hydrophobic organic chemicals (HOCs) is affected by various environmental factors, such as soil water saturation and drying. In this study, we used passive sampling to investigate the changes in the sorption capacity of SOM during a drying-wetting cycle using batch sorption experiments. Dried and non-dried peat mosses were used to observe the effect of the drying process on the sorption capacity of SOM at various levels of water saturation in soil pores. At soil with non-dried peat moss, the partition coefficient between the sampler and the soil (Ksampler/soil) slightly increased with decreasing water saturation. At soil with dried peat moss, however, there were almost no differences in the Ksampler/soil among different water saturations except for 100%. The soil organic carbon-water distribution coefficients (KOC) for dried peat moss were consistently larger than those for non-dried peat moss at all water saturation levels. However, the KOC values obtained at 100% water saturation for both non-dried and dried peat mosses differed only by 18-29%. For fluoranthene, there was only an 18% difference between the two KOC values at 100% water saturation, whereas it was 91% at 10% water saturation. This finding suggests that wetting SOM returns mostly its sorption capacity for HOCs after the increase in KOC caused by extreme drying. The range in sorption capacity obtained in this study showed the resilient margin of the sorption capacity of SOM for HOCs according to microclimatic changes that would occur constantly under environmental conditions.
One of the major environmental problems faced by today’s world is the contamination of soil, water, and air by toxic chemicals, and the distinct and unique role of microorganisms in the detoxification of polluted soil and environments is well recognized. Fungal mycelia have been primary governors for maintaining ecological equilibrium because they control the flow of nutrients. The strength and health of any ecosystem is a direct measure of its main components—the fungal populations and their interaction with other organisms such as plants, animals, and bacteria. Using fungi as the starter culture species in a mycoremediation project sets the stage for other organisms to participate in the rehabilitation process. The introduction of fungal mycelium into a polluted site triggers a flow of activity and begins to replenish the polluted ecosystem. Mycoremediation is an economically and environmentally sound alternative for bioremediation. It is not widely used at present, but this technology has wider potential than other technologies. Fungi perform a wide variety of functions in ecosystem and potentially have been proven to be clean, simple, and relatively inexpensive for environmental remediation. Examples of fungi used as mycoremediators are Pleurotus ostreatus ; Rhizopus arrhizus; Phanerochaete chrysosporium and P. sordida; and Tramates hirsuta and T. versicolor; and Lentinus edodes and L. tigrinus. Thus, this clean technology has greater potential and its untapped potential has to be fully exploited.
The filamentous fungi are proficient and copious producers of secondary metabolites. From the perspective of an organic chemist, the range and variety of chemical structures of these compounds is remarkable. Synthetic organic chemists have often used the very high structural complexity of fungal secondary metabolites to test their own abilities to mimic nature. From the perspective of a medicinal chemist, the diversity of compounds and structural types represents a pool of useful compounds often possessing unique biological properties. The range of structural types can, at first, appear baffling. However, most secondary metabolites produced by fungi fall into a relatively small number of classes: the alkaloids, derived from amines and amino acids; the terpenoids, derived from isopentenyl diphosphate; and the polyketides, generally derived from acetate. This system of classification is based on the biosynthetic origin of the compound in question, that is to say, a combination of the type of starting material and the type of chemical reactions used during biosynthesis. However, fungi also often combine different types of biosynthetic pathway during the manufacture of secondary metabolites. In Bristol, we have focused our efforts on understanding the biosynthesis of polyketides in fungi, but the inclusion of amino-acid derived moieties in the compounds we are interested in has also necessitated wider investigations.
Trichoderma-based biofungicides are a reality in agriculture, with more than 50 formulations available today as registered products worldwide. Several strategies have been applied to identify the main genes and compounds involved in this complex cross-talk between the fungal antagonist and the microbial pathogen, as mediated by the plant. Proteome and genome analysis have greatly enhanced our ability to conduct holistic and genome-based functional studies. We have identified and determined the role of a variety of novel genes and gene-products, including ABC transporters, enzymes and other proteins that produce or act as novel elicitors of induced systemic resistance, proteins recognized by the plant as avirulence factors, as well as molecules that generally activate the antagonistic activity in Trichoderma spp. We have cloned mycoparasitism-related promoters and used them in combination with GFP and other markers to study the interaction in vivo and in situ between Trichoderma and the fungal pathogen or the plant. Finally, we have transgenically improved the ability of the antagonist to kill other microbes and to activate plant defence mechanisms. Introduction Plant diseases caused by pathogenic fungi infections represent a major limiting factor for the cultivation and the conservation of agricultural plants of interest. The consequences of parasite attack result in both quantitative and qualitative reduction of crop production, large economic losses and represent a risk for human and animal health due to the accumulation of residues in the environment and mycotoxin contaminants in food products.
Introduction To apply suitable bioremediation techniques, an understanding of the physical, chemical and biological attributes of an environmental matrix is required. Effective bioremediation is based on optimizing these attributes to enhance the biodegradation of target pollutants. Fundamental to these processes is the concept of bioavailability and bioaccessibility of these pollutants at a suitable and relevant scale (Alexander, 2000; Semple et al., 2004). Environmental analyses are still based on chemical approaches that usually require an exhaustive extraction step prior to chromatographic analysis. This extracted fraction is commonly modelled to assess the portion that may cause harm to a particular target receptor. It is widely acknowledged that modelled values may be appropriate for human risk assessment (though inherently conservative) but yield little information for hazard assessment in a wider ecological or environmental context (Alexander, 2000). Many authors have demonstrated that chemical analysis alone does not provide information regarding the bioavailable fraction of compounds nor about their effects on selected biological receptors (Power et al., 1998; Hansen & Sørensen, 2001; Belkin, 2003; Paton & Killham, 2003). Biological assays are able to complement chemical analysis by considering the effects of all pollutants present in a sample, including those not detected by chemical analysis or those unable to be fitted in a model. Bioassays are used for monitoring the progress of bioremediation because they determine the bioavailable fraction of compounds that in part determines the biodegradability of a compound (Hansen & Sørensen, 2001; Paton & Killham, 2003). However, Semple et al.
Nematophagous and entomopathogenic fungi (NEF) comprise an important group of fungal parasites of invertebrates (FPI). NEF belong to a wide range of fungal taxa, but most of them are anamorphic fungi and facultative parasites. These fungi can infect, kill and digest nematodes and insects, respectively, which we will call their canonical, or normal, hosts. These hosts have barriers to the environment (eggshells and cuticles) that have common structural features. Therefore, the infection cycles share common strategies (e.g. adhesion to the host) or metabolites (e.g. proteases and chitinases for host penetration). Some species (e.g. Lecanicillium lecanii) can even be isolated from both infected nematodes and insects. The NEF may also infect other organisms (other fungi and plants) apart from their canonical hosts in a similar or different mode. We will use the term multimodal to describe the mode of action of these biological activities (Fig. 17.1). However, to date, the main emphasis in research has covered their mode of action on their canonical hosts (e.g. nematodes for nematophagous fungi). Many of these fungi are used for biological control of plant-parasitic organisms. In this review we will describe the NEF and their hosts in general terms (both canonical and non-canonical) at biological, ecological and physiological-molecular levels. We will also analyze the reasons for this multitrophic behaviour, trying to use a comparative approach of both types of hosts (canonical and non-canonical) and pathogens (nematophagous and entomopathogenic fungi) under an evolutionary perspective.
Polarized growth is the mechanism by which filamentous fungi extend their hyphae. Microtubules (MT) and filamentous actin (F-actin), in combination with their corresponding motor proteins, kinesins, dynein and myosins, play crucial roles in this process. The exact contribution of the MT cytoskeleton, however, is still under debate. In this review we will summarize recent advances in understanding the role of MTs and MT-dependent motor proteins in fungi with special emphasis on Aspergillus nidulans. Genetic, biochemical and cell biological approaches in A. nidulans and other fungi led to a modified view of many aspects within the past few years. There is increasing evidence that MT strings, which are visualized by immunostaining or GFP-tagging, consist of several MTs and their dynamics appears to be different in fast-growing hyphal tips as compared with young germlings. Whereas the spindle pole bodies were considered as the only or the main microtubule organizing centres (MTOCs) in filamentous fungi, it appears that several additional MTOCs are responsible for the generation of the MT array. In addition to new insights into the MT network and its dynamics, the roles of several kinesins have been elucidated recently and their interplay with dynein investigated. It became clear that MT functions are interwoven with those of the actin cytoskeleton and that three main structures are required for polarized growth, the Spitzenkörper (vesicle supply centre), the polarisome and probably cell end markers at the cortex. We propose a model for polarized growth, where the actin cytoskeleton and the polarisome are crucial for hyphal extension and the MT cytoskeleton continuously provides the building material within vesicles to the Spitzenkörper and determines growth directionality by delivery of cell end marker proteins.
Introduction Overview This paper explores the mechanisms of metal toxicity towards cells, specifically some advances being made in this area through work with the unicellular fungus, Saccharomyces cerevisiae. The two principal questions addressed here are: Is oxidative damage the cause of cellular metal toxicity? Why do individual cells exhibit widely differing metal resistances? Several powerful experimental tools are unique to S. cerevisiae among eukaryotes, and are being exploited to help elucidate the mechanism(s) of metal toxicity. Furthermore, in conjunction with its unicellular morphology, S. cerevisiae provides an ideal system with which to explore the topical problem of cell individuality, applied here to metal toxicity. This chapter provides an overview of these fields, illustrated with key findings from the author’s laboratory. Metals in the environment and relevance to fungi A wide range of industrial activities give rise to metal pollutants, which continue to be released into the environment at potentially harmful levels. Localized concentration of certain metals may also arise naturally. For example, toxic levels of the biologically essential metal copper are often associated with certain mineral ores as well as industrial or agricultural discharges. Cadmium is used widely in electroplating and galvanizing industries, as a colour pigment in paints and in batteries, and as a by-product of zinc and lead mining and smelting. Zinc, lead and other metals also may be released from similar types of sources.
Background In order to decrease dependence on petroleum, the United States Department of Energy (USDOE) Office of the Biomass Program (OBP) is investing in research and development to enable its vision of the biorefinery. The biorefinery will decrease the use of petroleum through conversion of biomass such as crops or agricultural waste into fuels and products. In 2004, the USDOE OBP asked researchers at the Pacific Northwest National Laboratory (PNNL) and the National Renewable Energy Laboratory (NREL) to prepare a list of the top ten building-block chemicals that can be derived from simple sugars by biological and/or chemical means. The resulting list of twelve building-block chemicals and the accompanying report (www.eere.energy.gov/biomass/pdfs/35523.pdf) form an informational foundation on which future DOE and industry bioproducts research will be built (Table 1.1). How do fungi fit into the biorefinery? Analysis of the ‘top ten’ study indicates that nine of the top twelve chemical building blocks are currently produced, or may potentially be produced, by fungal fermentation processes. However, a significant barrier to the use of bio-based products is the economic feasibility - fuels and products must be price-competitive with those derived from petroleum. An obvious way to decrease the costs of biobased products from fungi is to make fermentation strains more productive and processes more efficient. Traditional strain improvement programmes typically span a timescale measured in decades and process development done through the use of batch cultures is extremely labour intensive.
Epichloë endophytes (Epichloë/Neotyphodium species) are an important group of clavicipitaceous fungi that form symbiotic associations (symbiota) with temperate grasses of the Pooideae subfamily (Scott, 2001a; Schardl, Leuchtmann & Spiering, 2004). These biotrophic fungi systemically colonize the intercellular spaces of leaf primordia, leaf sheaths and culms of vegetative tissue and the inflorescence of reproductive tissues. The asexual Neotyphodium species have no external growth stage and consequently form symptomless associations with their grass host where they are vertically transmitted through the seed following colonization of the developing ovule. Most of the sexual Epichloë species are also transmitted vertically but because of their ability to form external stromata on inflorescence tissue, can also be transmitted horizontally (Leuchtmann & Schardl, 1998; Schardl & Leuchtmann, 1999). The mating system is heterothallic (outcrossing) and in nature is mediated by anthomyiid flies (Botanophila spp.), which transfer spermatia between stromata (Bultman et al., 1995; Bultman et al., 1998). Formation of perithecia and release of ascospores into the environment provides a source of vegetative hyphae that give rise to conidia that subsequently infect new hosts, probably by way of colonization of the stigma and style of the host inflorescence (Chung & Schardl, 1997). Taxonomy of epichloë endophytes At least nine different Epichloë species are recognized including E. typhina, a broad host range species (Schardl & Wilkinson, 2000) and E. festucae, a natural symbiont of Festuca spp. (Leuchtmann, Schardl & Siegel, 1994). E. festucae is also capable of forming compatible associations with perennial ryegrass, Lolium perenne (Christensen et al.
Genome resources for filamentous fungi have improved dramatically in the past few years. Since the publication of the N. crassa genome (Galagan et al., 2003) the pace has accelerated, with many projects completed or nearing completion (Table 6.1), and more underway. The number of researchers investigating the molecular genetics of filamentous fungi is relatively small, and the number of species very large, such that our efforts are spread rather thinly compared to the S. cerevisiae community, for example. Nevertheless, there are indications that these new resources will be extremely beneficial for mycology, and will attract new researchers into the field. Unlike yeasts, filamentous fungi are known for their ability to produce a wide variety of secondary metabolites, which are often of importance to man as useful drugs or harmful toxins (Keller, Turner & Bennett, 2005). Studies over the past 20 years have led to the characterization of some of the biosynthetic pathways and the gene clusters which encode them, for example, the penicillin/cephalosporin and aflatoxin/sterigmatocystin pathways (Brakhage, 1998; Hicks, Shimuzu & Keller, 2002). Since these gene clusters often span substantial regions of the genome, their isolation and sequencing was a major undertaking (Keller & Hohn, 1997). The genome sequences now emerging provide us with easily recognizable gene clusters as a starting point for further investigations, show us the entire secondary metabolic capacity of any species, and pose new questions about how the secondary metabolic repertoire of genera and species has evolved.
Several weeds such as the bindweeds Convolvulus arvensis and Calystegia sepium, which belong to the economically most important weeds, are difficult to control with conventional physical and chemical methods. Biological control with fungal biocontrol agents (FBCA) offers a promising alternative. However, the employment of such FBCAs implies not only the identification of highly effective strains and the development of cheap formulation and production techniques, but also an extensive risk assessment including tracking of FBCAs and their toxic metabolites in the environment. Stagonospora convolvuli strain LA39 effectively controls field and hedge bindweed in the field. For this strain formulation and application techniques were developed and currently markers for environmental tracking of the fungus are being designed. A major metabolite produced by LA39 is elsinochrome A (ELA). To assess the risk of ELA production by LA39, different methods, such as toxicity tests, stability tests and methods for environmental monitoring, were developed. Our results revealed that ELA is toxic to a wide array of organisms. However, ELA was never detected in LA39 treated bindweed or crop plants, and the ELA content in the applied biocontrol product is far too low to result in a toxic concentration in the environment. Furthermore, ELA is quickly degraded by sunlight. In conclusion, LA39 is a promising candidate for the development of a successful biocontrol product against bindweed. Harmful side effects of ELA production can be excluded.
Introduction The word ‘xenobiotic’ comes from the Greek word ‘xenos’, which means ‘foreign’, and describes foreign compounds that are in direct contact with a living environment. Man-made xenobiotics have been dispersed directly into the environment for many years, dumped as waste products, applied as agrochemicals, or as a result of major accidents, or indirectly, in the form of emissions from incineration processes. Xenobiotic structures are not readily recognized by existing degradative biological systems and have accumulated in the environment, and although substantial progress has been made in reducing chronic industrial derived pollution there is a growing bank of contaminated derelict industrial land - so called ‘brownfield sites’ - in towns and cities all over the country. In order that these sites may be repurposed for housing or for building up new commercial areas, powerful and cost-effective decontamination strategies are needed. The design of a decontamination strategy for a given site depends on the nature and concentration of contaminants, the site characteristics (especially water movement), and the extent of contamination. Directed bioremediation, an activity in which micro- and phyto-biological processes are used to degrade or transform contaminants into less toxic or non-toxic forms holds considerable potential as a strategy for in situ decontamination. It is generally cost-effective and less disruptive to soil and the natural landscape than ex situ techniques.
The research into bioremediation as well as the application of bioremediation methods in full-scale operations have a long time history in former Czechoslovakia and more recently in the Czech Republic. Whereas basic research into bioremediation and biodegradation is undertaken at universities and research institutes (Table 1), applied research is principally carried out by companies actively engaged in the bioremediation business.
The solutions of mathematical models for the estimation of the kinetic, and biokinetic parameters of naphthalene, anthracene and pyrene during degradation in surface and subsurface soils are presented in this work. The models were developed using the twin concepts of rate-determining step and steady-state approximation method. They described the biodegradation of single and a mixture of polycyclic aromatic hydrocarbons. Prediction of the concentration of the reactive PAHs with time was aided by fitting the models to the experimental data obtained from a soil microcosm reactor. Given an initial concentration of 100mg/L, approximately 2.9%, 1.9% and 1.4% of naphthalene, pyrene and anthracene present in the microcosm reactor at zero time were found to be utilized in a minute when the velocity of the reaction remained constant for the period.The rate-determining step model gave a better fit as its reaction rate constant (k) closely fitted the experimental values. Prediction by the steady state approximation model was not feasible as a comparative analysis of both single and multisubstrate results showed that the steady state approximation overestimates the biodegradation rates.Using the relative error method, results indicated that the rate-determining step model showed a deviation of 7.5%. The rate-determining step model was chosen because the differences in the model fits were small and its prediction of mixture experiment was more enhanced.
Pleurotus ostreatus, Trametes versicolor, Irpex lacteus, and Bjerkandera adusta were screened from 95 strains of ligninolytic fungi using decolorization of synthetic dyes and characterized for their growth and biodegradation of PAH and synthetic dyes. Growth on agar media was fast for all species, but only I. lacteus and P. ostreatus colonized soil. These two fungi significantly decolorized 9 out of 11 synthetic dyes tested on agar media. In liquid medium within 14 days, I. lacteus decolorized Methyl Red and Congo Red by 60%, and Remazol Brilliant Blue R (RBBR), Copper phtalocyanine and Bromophenol Blue by > 95%. I. lacteus removed 80% of the dye within 49 days in the RBBR-contaminated soil. Only T. versicolor and I. lacteus significantly degraded PAH in liquid medium, with removal rates after 28 days of 80 and 96% (anthracene), 0 and 27% (phenanthrene), 44 and 83% (pyrene), and 53-67% (fluoranthene), respectively. Removal rates using I. lacteus incubated for three months in soil contaminated with the same PAH were: 96% (anthracene), 67% (phenanthrene), 83% (pyrene), and 39% (fluoranthene), showing the strains's potential in the remediation of soil contaminated with toxic organopollutants.
Approximately 60% of the originally supplied anthracene (AC) was degraded in ligninolytic stationary cultures of selected white rot fungi within 21 days. All the white rot fungi tested oxidized AC to anthraquinone (AQ). Unlike Phanerochaete chrysosporium and strain Px, with Pleurotus ostreatus, Coriolopsis polyzona and Trametes versicolor, AQ did not accumulate in the cultures, indicating that AQ was degraded further and its degradation did not appear to be a rate-limiting step. However, P. ostreatus and C. polyzona failed to degrade AQ in the absence of AC. P. ostreatus, T. versicolor and strain Px did not produce lignin peroxidase (ligninase) (LIP) under the test conditions but oxidized AC to AQ suggesting that white rot fungi produce enzyme(s) other than LIP capable of oxidizing compounds with high ionization potential like AC. Moreover, in the case of Ph. chrysosporium and C. polyzona, AC degradation started earlier than the production of LIP. Veratryl alcohol (VA) seemed to be playing a role in AC oxidation catalyzed by LIP in Ph. chrysosporium.
The white-rot fungus Pleurotus ostreatus catalysed some humification of anthracene, benzo[a]pyrene and fluoranthene in two polycyclic aromatic hydrocarbon (PAH)-contaminated soils, one from a former manufactured gas facility and one from an abandoned electric coking plant. However, the extent of humification of PAH observed in these experiments was considerably less than that previously reported for other pollutants, such as chlorophenols. Addition of surfactants and related amendments significantly enhanced PAH removal from both soils by P. ostreatus, although humification of PAH was not always enhanced under these conditions.
Eight rapid Poly R-478 dye-decolorizing isolates from The Netherlands were screened in this study for the biodegradation of polycyclic aromatic hydrocarbons (PAH) supplied at 10 mg liter(-1). Several well-known ligninolytic culture collection strains, Phanerochaete chrysosporium BKM-F-1767, Trametes versicolor Paprican 52, and Bjerkandera adusta CBS 595.78 were tested in parallel. All of the strains significantly removed anthracene, and nine of the strains significantly removed benzo(a)pyrene beyond the limited losses observed in sterile liquid and HgCl2-poisoned fungus controls. One of the new isolates, Bjerkandera sp. strain Bos 55, was the best degrader of both anthracene and benzo(a)pyrene, removing 99.2 and 83.1% of these compounds after 28 days, respectively. Half of the strains, exemplified by strains of the genera Bjerkandera and Phanerochaete, converted anthracene to anthraquinone, which was found to be a dead-end metabolite, in high yields. The extracellular fluids of selected strains were shown to be implicated in this conversion. In contrast, four Trametes strains removed anthracene without significant accumulation of the quinone. The ability of Trametes strains to degrade anthraquinone was confirmed in this study. None of the strains accumulated PAH quinones during benzo(a)pyrene degradation. Biodegradation of PAH by the various strains was highly correlated to the rate by which they decolorized Poly R-478 dye, demonstrating that ligninolytic indicators are useful in screening for promising PAH-degrading white rot fungal strains.
Biodegradation of Orange II, Tropaeolin O, Congo Red, and Azure B in cultures of the white rot fungus, Phanerochaete chrysosporium, was demonstrated by decolarization of the culture medium, the extent of which was determined by monitoring the decrease in absorbance at or near the wavelength maximum for each dye. Metabolite formation was also monitored. Decolorization of these dyes was most extensive in ligninolytic cultures, but substantial decolorization also occurred in nonligninolytic cultures. Incubation with crude lignin peroxidase resulted in decolorization of Azure B, Orange II, and Tropaeolin O but not Congo Red, indicating that lignin peroxidase is not required in the initial step of Congo Red degradation.
The white rot fungus Phanerochaete chrysosporium degraded DDT [1,1,-bis(4-chlorophenyl)-2,2,2-trichloroethane], 3,4,3',4'-tetrachlorobiphenyl,
2,4,5,2',-4',5'-hexachlorobiphenyl, 2,3,7,8-tetrachlorodibenzo-p-dioxin, lindane (1,2,3,4,5,6-hexachlorocylohexane), and benzo[a]pyrene
to carbon dioxide. Model studies, based on the use of DDT, suggest that the ability of Phanerochaete chrysosporium to metabolize
these compounds is dependent on the extracellular lignin-degrading enzyme system of this fungus.
White rot fungi can oxidize high-molecular-weight polycyclic aromatic hydrocarbons (PAH) rapidly to polar metabolites, but only limited mineralization takes place. The objectives of this study were to determine if the polar metabolites can be readily mineralized by indigenous microflora from several inoculum sources, such as activated sludge, forest soils, and PAH-adapted sediment sludge, and to determine if such metabolites have decreased mutagenicity compared to the mutagenicity of the parent PAH. 14C-radiolabeled benzo[a]pyrene was subjected to oxidation by the white rot fungus Bjerkandera sp. strain BOS55. After 15 days, up to 8.5% of the [14C]benzo[a]pyrene was recovered as 14CO2 in fungal cultures, up to 73% was recovered as water-soluble metabolites, and only 4% remained soluble in dibutyl ether. Thin-layer chromatography analysis revealed that many polar fluorescent metabolites accumulated. Addition of indigenous microflora to fungal cultures with oxidized benzo[a]pyrene on day 15 resulted in an initially rapid increase in the level of 14CO2 recovery to a maximal value of 34% by the end of the experiments (>150 days), and the level of water-soluble label decreased to 16% of the initial level. In fungal cultures not inoculated with microflora, the level of 14CO2 recovery increased to 13.5%, while the level of recovery of water-soluble metabolites remained as high as 61%. No large differences in 14CO2 production were observed with several inocula, showing that some polar metabolites of fungal benzo[a]pyrene oxidation were readily degraded by indigenous microorganisms, while other metabolites were not. Of the inocula tested, only PAH-adapted sediment sludge was capable of directly mineralizing intact benzo[a]pyrene, albeit at a lower rate and to a lesser extent than the mineralization observed after combined treatment with white rot fungi and indigenous microflora. Fungal oxidation of benzo[a]pyrene resulted in rapid and almost complete elimination of its high mutagenic potential, as observed in the Salmonella typhimurium revertant test performed with strains TA100 and TA98. Moreover, no direct mutagenic metabolite could be detected during fungal oxidation. The remaining weak mutagenic activity of fungal cultures containing benzo[a]pyrene metabolites towards strain TA98 was further decreased by subsequent incubations with indigenous microflora.
White-rot fungi, Coriolus versicolor and Funalia trogii, produced laccase on media with diluted olive-oil mill wastewater and vinasse. Addition of spent cotton stalks enhanced the laccase activity with a maximum after 12 d of cultivation.
The mineralization of [14C]pyrene in sterilized and non-sterile soil was investigated using the wood-decaying fungi Kuehneromyces mutabilis and Agrocybe aegerita in a period of 63 days. In sterilized soil 5.1% and 1.5% of the pyrene was mineralized to 14CO2 by K. mutabilis and by A. aegerita, respectively. In non-sterile soil, 27.3% of pyrene was mineralized by indigenous soil microflora including a Mycobacterium gilvum strain. During soil inoculation with fungi the mineralization was higher (47.7% for K. mutabilis and 38.5% for A. aegerita). For a mass balance analysis the soil was extracted with toluene and methanolic KOH (humic acid extraction). Considering the sum of mineralization and formation of bound residues (nonextractable radioactivity), about 50% (sterilized soil) and 75% (non-sterile soil) of pyrene were eliminated by K. mutabilis. In comparison with indigenous soil microflora, K. mutabilis enhanced pyrene elimination up to 42%.
The fate of Streptomyces lividans lysogens was studied in sterile and nonsterile soil microcosms. It was found that in sterile soil lysogens grew as well as the parental strain. However, in nonsterile soil, numbers of the lysogen decreased rapidly, indicating a decreased fitness when compared to the original organism. In addition, the release of this phage from a lysogen and its subsequent infection and lysogenisation of a recipient strain was demonstrated in sterile soil.
Ecotoxicological assessments of contaminated soil aim to understand the effect of introduced chemicals on the soil flora and fauna. Ecotoxicity test methods were developed and conducted on hydrocarbon-contaminated soils (<5,000–30,000 mg/kg total petroleum hydrocarbon) and on adjacent uncontaminated control soils from eight field locations. Tests included 7-d, 14-d, and chronic survival tests and reproduction assays for the earthworm (Eisenia fetida) and seed germination, root length, and plant growth assays for corn, lettuce, mustard, and wheat. Species-specific responses were observed with no-observed effect concentrations (NOECs) ranging from <1 to 100% contaminated soil. The 14-d earthworm survival NOEC was equal to or greater than the reproduction NOEC values for numbers of cocoons and juveniles, which were similar to one another. Cocoon and juvenile production varied among the control soils. Germination and root length NOECs for mustard and lettuce were less than NOECs for corn and wheat. Root length NOECs were similar to or less than seed germination NOECs. Statistically significant correlations (p < 0.05) for earthworm survival and seed germination as a function of hydrocarbon measurements were found. The 14-d earthworm survival and the seed germination tests are recommended for use in the context of a risk-based framework for the ecological assessment of contaminated sites.
The mineralization of [14C]pyrene in sterilized and non-sterile soil was investigated using the wood-decaying fungi Kuehneromyces mutabilis and Agrocybe aegerita in a period of 63 days. In sterilized soil 5.1% and 1.5% of the pyrene was mineralized to 14CO2 by K. mutabilis and by A. aegerita, respectively. In non-sterile soil, 27.3% of pyrene was mineralized by indigenous soil microflora including a Mycobacterium gilvum strain. During soil inoculation with fungi the mineralization was higher (47.7% for K. mutabilis and 38.5% for A. aegerita). For a mass balance analysis the soil was extracted with toluene and methanolic KOH (humic acid extraction). Considering the sum of mineralization and formation of bound residues (non-extractable radioactivity), about 50% (sterilized soil) and 75% (non-sterile soil) of pyrene were eliminated by K. mutabilis. In comparison with indigenous soil microflora, K. mutabilis enhanced pyrene elimination up to 42%.
Phanerochaete chrysosporium decolourised 6 out of 9 synthetic textile dyes tested in the presence of glucose. 3 textile dyes were decolourised in the absence of a primary carbon source. Decolourisation of an artificial textile effluent was complete after 7 days, however, the role of lignin peroxidase was unclear.
The abilities of the white-rot fungi Chrysosporium lignorum, Trametes versicolor, Phanerochaete chrysosporium and Stereum hirsutum to mineralize 3,4-dichloroaniline, dieldrin and phenanthrene were investigated. S. hirsutum did not mineralize any of the test compounds but the other strains partly mineralized them all to varying degrees. The relative degradation rates per unit biomass were T. versicolor > C. lignorum > P. chrysosporium. Evidence was obtained for the production of water-soluble metabolic intermediates but no attempt was made to characterize these. It was found that mineral salts-glucose medium supplemented with trace mineral nutrients, vitamins and 1.5 mm 3,4-dimethoxybenzyl alcohol (veratryl alcohol) resulted in the highest mineralization rate. At no time in these experiments was there detectable extracellular ligninase (lignin peroxidase) activity.
Soil samples were collected from sites contaminated with creosote but differing in the length of time since cessation of production. They were used to evaluate in laboratory experiments the effect of aging and the significance of adding metabolically competent bacteria on the loss of indigenous fluoranthene and pyrene. Incubation was carried out with or without addition of cells grown with 3-methylbenzoate. Control experiments used spiked contaminants to confirm the metabolic competence of the added bacteria, and azide was used to exclude the role of abiotic reactions. It was concluded that there was no advantage in adding metabolically competent bacteria to facilitate degradation of these PAH contaminants in soil, and that aging was a primary factor in determining the success of bioremediation. Indigenous benzo[e]phenanthrylene, benzo[ghi]perylene, and benzo[a]pyrene were recalcitrant in the younger soil; and in view of the results for fluoranthene and pyrene, they may, therefore, be presumed to be recalcitrant in aged soils.
Biodegradation of polycyclic aromatic hydrocarbon (PAH) was investigated in the whole matrix and in the different aggregate size fractions of a sandy soil contaminated by a mixture of 8 PAHs and incubated at water holding capacity. The distribution of PAHs and of phenanthrene-degrading bacteria were determined in the bulk soil and in 4 size aggregate fractions corresponding to sand, coarse silt, fine silt and clay. The microbial communities able to degrade phenanthrene were detected at a similar level in the different aggregate fractions of the soil before contamination. After soil contamination and incubation, a significant growth of bacteria was observed and their distribution within aggregates was modified. Bacterial communities of phenanthrene-degraders were present in a higher density in the aggregates corresponding to sand (2000–50 μm) and clay (<2 μm). Chemical analysis show that remaining PAHs (low and high molecular weight) were much more concentrated in the fine soil fractions (fine silt and clay) and were present at a very low content in the larger aggregate size fractions. The interactions of well defined aggregates with PAHs and bacteria were also studied using phenanthrene as PAH model substrate and individual aggregates corresponding to sand and clay size fractions. Incubation of sand and clay aggregate fractions enriched with phenanthrene in the presence of a bacterial isolate NAH1 led to the simultaneous solubilization and biodegradation of phenanthrene. Differences in amounts of solubilized phenanthrene between sand and clay aggregate size fractions would be related to difference in adsorption capacities of phenanthrene by clay and sand aggregates.
Polycyclic aromatic hydrocarbon (PAH) biodegradation was investigated in contaminated soils from two different industrial sites under simulated land treatment conditions. Soil samples from a former impregnation plant (soil A) showed high degradation rates of PAHs by the autochthonous microorganisms, whereas PAHs in material of a closed-down coking plant (soil B) were not degraded even after inoculation with bacteria known to effectively degrade PAHs. As rapid PAH biodegradation in soil B was observed after PAHs were extracted and restored into the extracted soil material, the kind of PAH binding in soil B appears to completely prevent biodegradation. Sorption of PAHs onto extracted material of soil B follows a two-phase process (fast and slow); the latter is discussed in terms of migration of PAHs into soil organic matter, representing less accessible sites within the soil matrix. Such sorbed PAHs are suggested to be non-bioavailable and thus non-biodegradable. By eluting soil B with water, no biotoxicity, assayed as inhibition of bioluminescence, was detected in the aqueous phase. When treating soil A analogously, a distinct toxicity was observed, which was reduced relative to the amount of activated carbon added to the soil material. The data suggest that sorption of organic pollutants onto soil organic matter significantly affects biodegradability as well as biotoxicity.
The ligninolytic fungus Phanerochaete chrysosporium oxidized phenanthrene and phenanthrene-9,10-quinone (PQ) at their C-9 and C-10 positions to give a ring-fission product, 2,2'-diphenic acid (DPA), which was identified in chromatographic and isotope dilution experiments. DPA formation from phenanthrene was somewhat greater in low-nitrogen (ligninolytic) cultures than in high-nitrogen (nonligninolytic) cultures and did not occur in uninoculated cultures. The oxidation of PQ to DPA involved both fungal and abiotic mechanisms, was unaffected by the level of nitrogen added, and was significantly faster than the cleavage of phenanthrene to DPA. Phenanthrene-trans-9,10-dihydrodiol, which was previously shown to be the principal phenanthrene metabolite in nonligninolytic P. chrysosporium cultures, was not formed in the ligninolytic cultures employed here. These results suggest that phenanthrene degradation by ligninolytic P. chrysosporium proceeds in order from phenanthrene----PQ----DPA, involves both ligninolytic and nonligninolytic enzymes, and is not initiated by a classical microsomal cytochrome P-450. The extracellular lignin peroxidases of P. chrysosporium were not able to oxidize phenanthrene in vitro and therefore are also unlikely to catalyze the first step of phenanthrene degradation in vivo. Both phenanthrene and PQ were mineralized to similar extents by the fungus, which supports the intermediacy of PQ in phenanthrene degradation, but both compounds were mineralized significantly less than the structurally related lignin peroxidase substrate pyrene was.
Soil samples from an agricultural field contaminated with 10 ppm 14C-benz(a)anthracene in glass tubes were brought into contact with cultures of wood-rotting fungi, precultivated on wheat straw substrate. Forty-five strains of white-rot fungi and four brown-rot fungi were tested for their ability to colonize the soil and to mineralize 14C-benz(a)anthracene to 14CO2 within a 20-week incubation time. Twenty-two white-rot fungi and all brown-rot fungi were unable to colonize the soil. Twenty-three strains of white-rot fungi, all belonging to the genus Pleurotus, colonized the soil. During the experiment the non-colonizing fungi and their substrate disintegrated more and more to a nonstructured pulp from which water diffused into the soil. The same phenomenon was observed in the control which contained only straw without fungus and contaminated soil. In samples with colonizing fungi the substrate as well as the mycelia in the soil remained visibly unchanged during the entire experiment. Surprisingly, most samples with fungi not colonizing the soil and the control without fungus liberated between 40 and 58% of the applied radioactivity as 14CO2 whereas the samples with the colonizing fungi respired only 15-25% as 14CO2. This was 3-5 times more 14CO2 than that liberated from the control (4.9%) which contained only contaminated soil without straw and fungus. A similar result was obtained with selected colonizing and noncolonizing fungi and soil contaminated with 10 ppm 14C-pyrene. However, in pure culture studies in which 14C-pyrene was added to the straw substrate, Pleurotus sp. (P2), as a representative of the colonizing fungi, mineralized 40.3% of the added radioactivity to 14CO2. The noncolonizing fungi Dichomitus squalens and Flammulina velutipes liberated only 17.2 or 1.7%, respectively, as 14CO2. These results lead to the hypothesis that the native soil microflora stimulated by the formed products of straw lysis is responsible for high degradation rates found with noncolonizing fungi.
As part of a study conducted on the fate of xenobiotics in the environment, a selection of 100 strains of micromycetes (Ascomycetes, Basidiomycetes and Yeasts) have been cultivated in liquid synthetic medium with 3 phenylurea herbicides: chlortoluron and isoproturon (100mg L-1) and diuron (20mg L-1). While 17 strains depleted isoproturon over 50% only 4 depleted diuron and 2 chlortoluron at the same level. The best results were obtained with Bjerkandera adusta and Oxysporus sp which were the most efficient towards the 3 substrates. After 2 weeks Bjerkandera adusta depleted chlortoluron 98%, diuron 92% and isoproturon 88%.
The rate and efficiency of decolorization of poly R-478- or Remazol Brilliant Blue R (RBBR)-containing agar plates (200 microg x g(-1)) were tested to evaluate the dye degradation activity in a total of 103 wood-rotting fungal strains. Best strains were able to completely decolorize plates within 10 days at 28 degrees C. Irpex lacteus and Pleurotus ostreatus were selected and used for degradation of six different groups of dyes (azo, diazo, anthraquinone-based, heterocyclic, triphenylmethane, phthalocyanine) on agar plates. Both fungi efficiently degraded dyes from all groups. Removal of RBBR, Bromophenol blue, Cu-phthalocyanine, Methyl red and Congo red was studied with I. lacteus also in liquid medium. Within 14 days, the following color reductions were attained: RBBR 93%, Bromophenol blue 100%, Cu-phthalocyanine 98%, Methyl red 56%, Congo red 58%. The ability of I. lacteus to degrade RBBR spiked into sterile soil was checked, the removal being 77% of the dye added within 6 weeks. The capacity of selected white rot fungal species to remove efficiently diverse synthetic dyes from water and soil environments is documented.
Agitation, temperature, inoculum size, initial pH and pH of buffered medium affected the decolorization of Orange II dye by Coriolus versicolor and Funalia trogii. The optimum temperature and initial pH value for decolorization were 30 degrees C and 6.5-7.0, respectively; pH 4.5 was the most efficient in buffered cultures. High decolorization extents were reached at all agitation rates. At an inoculum size of more than 1 mL, the extent of decolorization changed only slightly. High extents were obtained using immobilized fungi at repeated batch mode.
During investigation of biodegradation in soil, we have found that classical or standard techniques for introduction of compounds and the growth of fungus into soil are ill-defined and inadequate. In response to this deficiency, a method for controlled introduction of extractable compounds and for the growth of fungus in soils has been developed. This method was successfully used to study the degradation of fluorene in soil by the fungus Phanerochaete chrysosporium.
Comparision of abilities of white-rot fungi to mineralize selected xenobiotic compounds
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Phytoremediation and Innovative Strategies for Specialized Remedial Applications
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