Figure - available from: Applied Microbiology and Biotechnology
This content is subject to copyright. Terms and conditions apply.
Growth of the bacterial strain TWSL_4 and bioremoval of metal ions Cr (a), Zn (b), Pb (c), and Fe (d) in the effluent. Abiotic controls used for the assay: G-C, R-C-Cr, R-C-Zn, R-C-Pb, and R-C-Fe (GraphPad Prism software)
Source publication
Bioremediation of toxic metal ions using bacterial strains is a promising tool. Metal binding motifs in microbial proteins are involved in the regulation and transport of such toxic metals for metal detoxification. A bacterial strain designated TWSL_4 with metal (Cu, Cd, and Pb) resistance and removal ability was isolated and identified as a Bacill...
Citations
... The czcCBA complex is responsible for the efflux of Cd at the cell membrane (Ma et al., 2009). Numerous studies have shown that these functional genes are prevalent in the low-abundance rhizobacteria of the T1 group, such as Bacillus (Kumari et al., 2021), Lysinibacillus (Peña-Montenegro and Dussán, 2013), and Chitinophaga . Therefore, the accumulation of genes involved in Cd efflux and stress response appears to be a vital survival strategy for the rhizobacterial community in defense against Cd uptake. ...
Optimizing planting spacing is a common agricultural practice for enhancing rice growth. However, its effect on the accumulation of cadmium (Cd) and phenanthrene (Phen) in soil-rice systems and the response mechanisms of rhizobacteria to co-contaminants remain unclear. This study found that reducing rice planting spacing to 5 cm and 10 cm significantly decreased the bioavailability of Cd (by 7.9 %–29.5 %) and Phen (by 12.9 %–47.6 %) in the rhizosphere soil by converting them into insoluble forms. The increased accumulation of Cd and Phen in roots and iron plaques (IPs) ultimately led to decreased Cd (by 32.2 %–39.9 %) and Phen (by 4.2 %–17.3 %) levels in brown rice, and also significantly affected the composition of rhizobacteria. Specifically, reducing rice planting spacing increased the abundance of low-abundance but core rhizobacteria in the rhizosphere soil and IPs, including Bacillus, Clostridium, Sphingomonas, Paenibacillus, and Leifsonia. These low-abundance but core rhizobacteria exhibited enhanced metabolic capacities for Cd and Phen, accompanied by increased abundances of Cd-resistance genes (e.g., czcC and czcB) and Phen-degradation genes (e.g., pahE4 and pahE1) within the rhizosphere soil and IPs. Reduced planting spacing had no noticeable impact on rice biomass. These findings provide new insights into the role of low-abundance but core rhizobacterial communities in Cd and Phen uptake by rice, highlighting the potential of reduced planting spacing as an eco-friendly strategy for ensuring the safety of rice production on contaminated paddy soils.
... To screen for possible metal tolerant bacterial strains, present in the effluent, 50 μl fr om pr epar ed dilutions (10 −1 -10 −6 ) wer e separ atel y spr ead on LB a gar plates . After incubation (o vernight, 37 • C), wellisolated distinct bacterial colonies were restreaked and a few isolated bacterial strains were screened for heavy metal resistivity by observing their growth on multimetal enriched LB agar plates [Cd 2 + , Pb 2 + , and Cu 2 + (20 mg/l)] for 2 days (Benson 2002, Kumari et al. 2021a. A bacterial strain designated TWSL_22 , which grew w ell w as selected as a most pr omising str ain for further anal ysis. ...
A heavy metal resistant bacterial strain, TWSL_22 was isolated from an industrial effluent sample and tested for heavy metal tolerance and resistance. The strain was molecularly characterized as Staphylococcus epidermidis based on 16S rRNA gene analysis and the sequence was deposited in the NCBI repository (Accession number KT184893.1). Metal removal activity (P < 0.001) of TWSL_22 was 99.99 ± 0.001%, 74.43 ± 2.51% and 51.16 ± 4.17% for Cd, Pb and Cu respectively. Highest MIC was observed for Cd. Antibiotic susceptibility assays revealed the strain TWSL_22 to be resistant to several antibiotics. The strain was screened for possible heavy metal resistant genes and presence of cadA, copA and cadD was confirmed by PCR. A DNA fragment containing complete sequence of cadD (618 bp) was isolated and cloned into pET 21a(+), transformed into E. coli BL21 and designated as E. coli/cadDET. E. coli/cadDET showed high metal tolerance capacity and could remove over 82% of heavy metals (Zn2+, Cd2+, Cu2+, Cr3+) in the industrial effluent.
... For this reason, there is a growing interest in the use of bioremediation, either through the use of plants, microorganisms or both (phytorhizoremediation) for the recovery of these environments [5,6,[48][49][50]. There are multiple studies on the use of microorganisms for the recovery of heavy-metal-contaminated areas [5,8,48,[51][52][53][54] and the benefits of adding PGPB that favor the process. Likewise, it is important to know the impact that their addition generates in the composition and biological diversity of the communities that host them, as well as the impact that the addition of microorganisms can exert on the expression of AR mechanisms of microbial communities. ...
The emergence of antibiotic resistance (AR) poses a threat to the “One Health” approach. Likewise, mercury (Hg) pollution is a serious environmental and public health problem. Its ability to biomagnify through trophic levels induces numerous pathologies in humans. As well, it is known that Hg-resistance genes and AR genes are co-selected. The use of plant-growth-promoting bacteria (PGPB) can improve plant adaptation, decontamination of toxic compounds and control of AR dispersal. The cenoantibiogram, a technique that allows estimating the minimum inhibitory concentration (MIC) of a microbial community, has been postulated as a tool to effectively evaluate the evolution of a soil. The present study uses the metagenomics of 16S rRNA gene amplicons to understand the distribution of the microbial soil community prior to bacterial inoculation, and the cenoantibiogram technique to evaluate the ability of four PGPB and their consortia to minimize antibiotic resistance in the rhizosphere of Lupinus albus var. Orden Dorado grown in Hg-contaminated soils. Results showed that the addition of A1 strain (Brevibacterium frigoritolerans) and its consortia with A2, B1 and B2 strains reduced the edaphic community´s MIC against cephalosporins, ertapenem and tigecycline. The metagenomic study revealed that the high MIC of non-inoculated soils could be explained by the bacteria which belong to the detected taxa,. showing a high prevalence of Proteobacteria, Cyanobacteria and Actinobacteria.
... Gram-positive bacteria Bacillus megaterium are found in soils and are members of the microbiome of several host plants around the world, acting mainly as biological control agents [10][11][12][13][14]. These strains effectively colonize soils and plant tissues and produce a wide range of biologically active compounds that are involved in promoting plant growth [15][16][17][18][19][20][21] and antiphytopathogenic activity [22]. Bacillus species are also a source of a wide range of metabolites and enzymes of biotechnological and industrial interest [23]. ...
The article presents the results of studying the influence of Bacillus megaterium on the growth and development of Gossypium hirsutum cotton plant in the field conditions of the Astrakhan Region. In the wild plants have to cope with several adverse environmental conditions, such as water scarcity, high salt concentrations in the soil, extreme temperatures, nutrient deficiencies and pathogen attacks. However, plants can interact with several soil microorganisms, including plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi, which make the plant more resistant to such stresses. Bacillus-based products represent the most important class of microbial products for phytosanitary use available on the market. Field studies and microbiological analysis of the soil were carried out on the basis of the All-Russian Research Institute of Irrigated Horticulture and Melon Growing (VNIIOB) and Astrakhan State University. To compare the results, in the experiment the chemical mineral fertilizer Amofoska was used in the concentration of the working solution. Distilled water was used as a control substance. The weight of the crop was calculated at the end of the vegetation season. The research revealed that Bacillus megaterium has growth-promoting effect on cotton culture. Germination of seeds treated with bacillus was 96%. Plant biometrics indicate that plants treated with bacillus show the highest values in terms of leaf weight, leaf area and root length relative to the control. Thus, the number of buds and flowers increased by 5.1 and 3.1 pieces in comparison to the control sample and the one treated with mineral fertilizer, respectively. The length of the root also increased by 9.8 and 2.4 cm. The weight of cotton treated with bacillus exceeds the control variant by 46 g. and mineral fertilizer by 48.4 g, respectively. When abundantly poured for the second time, this indicator exceeded the weight of the control sample by 8 g and after treatment with mineral fertilizer - by 32 g.
... cadA gene codes for a 727 amino acid protein with similarity to P-type ATPases that can protect cells from cadmium accumulation by functioning as an energy-dependent efflux ATPase across the cell membranes. cadC gene, encoding a protein of 122 aa, is the transcription regulator of cadA gene [8,9,10,11,12]. This resistance mechanism works via efflux Cd +2 outside the cell with ATPase activity (cadA). ...
Background
Cadmium (Cd²⁺) is one of the highly toxic heavy metals and is considered as a carcinogenic agent. Our aim was to confirm Frankia alni ACN14a ability to resist Cd²⁺ and determine the genes involved in the resistance.
Results
Up to 10 and 22 times in Cd²⁺ accumulation were detected in F. alni ACN14a and Frankia casuarinae CcI3 hyphae when exposure to 1 mM, respectively. Scanning Electron Microscopy (SEM) exhibited a stable Cd²⁺ precipitate to the cell surface and increase in Cd²⁺ weight level reached attached 16.45 % when evaluated with SEM-EDAX analysis. Potential two Cd²⁺ operons were identified: 1- cadCA operon encoding a copper-transporting P-type ATPase A (cadA, FRAAL0989), ArsR family regulator (cadC, FRAAL0988) with 37- and 70-fold increases in their expression by qRT-PCR, respectively; 2- cadB/DX which encodes a putative cobalt-zinc-cadmium resistance protein (cadD, FRAAL3628) and heavy metal-associated domain protein (cadX, FRAAL3626) with 22- and 16-fold up-regulation when exposure to Cd²⁺-stress.
Conclusions
Cd²⁺ tolerance by F. alni ACN14a involved effluxing Cd²⁺ outside the cells and binding it to the membrane surface. Our results indicate the existence of two cadmium-resistance mechanisms in Frankia strains which support the idea of using them as bioremediation agent.
... However, except for the mercury resistance operon (mer), which has been fully studied (21,22), few studies of metal resistance determinants and mechanisms in B. megaterium have been reported. These studies include a description of resistance genes for Cd (17,23,24), Cu (25), Pb (17), and Ni (26). This work was focused on the characterization of the Hg-tolerant bacterial strain HgT21, isolated from the rhizosphere of a metalcontaminated soil. ...
... cadA encodes a cadmium-translocating Ptype ATPase (CadA), a homologous protein of ZntA, which is considered a multipurpose metal-exporting pump for the extrusion of Zn 21 , Cd 21 , Ag 21 , and Pb 21 (65). The cadA gene is a component of the well-described cadmium resistance operon cadAC encountered in Gram-positive bacteria, including S. aureus (plasmid pI258), Listeria monocytogenes, B. megaterium, and other Bacillus species (24,(66)(67)(68). In the CadAC system, the expression of cadA is tightly controlled by the regulatory protein CadC, a Cd 21 /Pb 21 /Zn 21 responsive repressor encoded by cadC located downstream of cadA (67). ...
Metal-polluted environments are natural sources of a wide variety of PGPB adapted to cope with toxic metal concentrations. In this work, the bacterial strain Bacillus megaterium HgT21 was isolated from metal-contaminated soil and is proposed as a model for the study of metal multiresistance in spore-forming Gram-positive bacteria due to the presence of a variety of metal resistance-associated genes similar to those encountered in the metal multiresistant Gram-negative Cupriavidus metallidurans CH34.
... Spearman correlation analysis further verified the relationship between HMs availability and bacterial diversity. Many functional bacteria in NRMA could have contributed to HMs detoxification, such as Pseudomonas, Bacillus, and Acinetobacter Kumari et al., 2021;Srut et al., 2019). Pseudomonas and Acinetobacter can not only reduce Cr 6+ to Cr 3+ but also immobilize Cu 2+ (Sun et al., 2020). ...
Heavy metals (HMs) in husbandry waste have become a serious concern. To understand the impact of bioaugmentation on HMs-influenced composting, HMs-influenced swine manure was composted with nitrogen-retaining microbial agents (NRMA). Compared with control (CG), compost with NRMA (EG) presented a significantly lower HOAc extractable Cd (23.10%), Cu (48.15%), Cr (82.79%), Pb (4.49%), and Zn (29.15%) (P < 0.05). EG also showed 5 days longer high-temperature period during composting. After composting, EG had a 4.14% higher TN (27.93 g/kg) than CG (26.82 g/kg) but a 32.26% lower NH4⁺-N. The change in pH and NH4⁺-N driven by microbial activity was found the main reason for HMs bioavailability decrease. NRMA greatly strengthened the enrichment of HMs resistant bacteria such as Actinobacteriota and Chloroflexi in EG, whose abundance increased by 21.23% and 2473.75% compared with day 0 after composting, respectively. HMs resistance genes, such as copA (increased by 936.84%), czcA (62.95%), cadC (63.06%), and pbrT (684.08%), and chrB (16.89%), also elevated in EG than CG. Eventually, NRMA was able to regulate the microbial composition of manure composting under HMs impact, reduce HMs toxicity, and enhance composting efficiency, which should be considered for the safe disposal of such polluted waste.
... B. megaterium is also considered as a potential microbial fertilizer, and is widely used in soil improvement and has great application value in solubilizing phosphorus and promoting plant root growth (Makki and Abdl-Kadhim, 2021). In addition, B. megaterium has also been found to have outstanding effects in the field of bioremediation, such as heavy metal repair and oil removal (Khan and Alka, 2011;Kumari et al., 2021). However, there are few studies on the degradation of pesticides, and only the biodegradation of methamidophos and monosultap has been reported so far (Birolli et al., 2021). ...
As a common pyrethroid insecticide, allethrin is widely used for various purposes in agriculture and home applications. At present, allethrin residues have been frequently detected worldwide, yet little is known about the kinetics and degradation mechanisms of this insecticide. In this study, a highly efficient allethrin-degrading bacterium, Bacillus megaterium strain HLJ7, was obtained through enrichment culture technology. Strain HLJ7 can remove 96.5% of 50 mg L⁻¹ allethrin in minimal medium within 11 days. The first-order kinetic analysis of degradation demonstrated that the half-life of allethrin degradation by strain HLJ7 was 3.56 days, which was significantly shorter than the 55.89 days of the control. The Box–Behnken design of the response surface method optimized the degradation conditions for strain HLJ7: temperature 32.18 °C, pH value 7.52, and inoculation amount 1.31 × 10⁷ CFU mL⁻¹. Using Andrews equation, the optimal concentration of strain HLJ7 to metabolize allethrin was determined to be 21.15 mg L⁻¹, and the maximum specific degradation rate (qmax), half-rate constant (Ks) and inhibition coefficient (Ki) were calculated to be 1.80 d⁻¹, 1.85 mg L⁻¹ and 68.13 mg L⁻¹, respectively. Gas chromatography-mass spectrometry identified five intermediate metabolites, suggesting that allethrin could be degraded firstly by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and subsequent metabolism. The results of soil remediation experiments showed that strain HLJ7 has excellent bioremediation potential in the soils. After 15 days of treatment, about 70.8% of the initial allethrin (50 mg kg⁻¹) was removed and converted into nontoxic intermediate metabolites, and its half-life was significantly reduced in the soils. Taken together, these findings shed light on the degradation mechanisms of allethrin and also highlight the promising potentials of B. megaterium HLJ7 in bioremediation of allethrin-comtaminated environment.
... Cooper heavy particles were also found to be reduced with Bacillus cereus strain (Migocka, 2015).One study also revealed that the microbes are able to degrade heavy metals like zinc, mercury and are also have ability to show many antibiotic drug resistant ability and tolerance (Naik et al. 2012). Bacillus strains are able to show biomonitoring by reducing toxic effects of heavy metals like zinc, copper, lead, iron and mercury (Kumari et al., 2021). This study reveals that bacillus strains are capable for growing at unfavorable conditions and can be utilized for long term bioremediation (Pattnaik et al., 2022). ...
Nature is the precious gift for every organism on the earth but, only few species are taking benefits and rest are suffering from scarcity of natural resources because of over exploitation. There exist numbers of hazardous pollutants in environment that are required to eradicate for sustainable use of natural resources. To overcome these pollutants researchers introduced bioremediation with microorganisms. This paper has been prepared by collecting data from various research articles to show numerous applications of bacillus species for sustaining environment. The article is unique from other research studies as it elaborates removal of different pollution causing elements such heavy metals, soil contaminants, removal of dye contaminants from the environment. Although there are large numbers of microbial species to degrade pollutants but according to recent researches, Bacillus is more prominent among all bacterial species. Researchers have proved that Bacillus are safer and cheaper source for conserving environment and reduce toxics from environment. Removal of heavy metals such as cadmium, nickel, copper can be done with the help of Bacillus cereus. In waste water treatment, Bacillus licheniformis and Bacillus acidophilus are also responsible for reducing nitrogenous components like phosphates, nitrites and ammonia.
... Bacteria can live all over the biosphere because of their remarkable adaptability to environmental changes, stress conditions (such as toxic metal stress) and evolving many resistant mechanisms to maintain homeostasis (Ayangbenro et al., 2018). Therefore, bacteria in metal contaminated sites (such as in industrial effluents), have evolved tolerant systems which have a higher potential to be used in metal bioremediation (Kapahi et al., 2019;Kumari et al., 2021). Isolation of heavy metal resistant microbes and the identification of genes involved would benefit further research into bioremediation and biomonitoring. ...
... Half-life (t1/2) was defined as the time taken for the metal concentration of the medium to reduce to 50% of its initial concentration (Durrani et al., 2014). The Bioremoval percentage (BR%) of metal ions and the metal ion Removal Rate (RR) by the strain were calculated using the following equations (Kumari et al., 2021): ...
... Several strains of B. cereus with metal resistance and bioremediation ability have been reported previously (Igiri et al., 2018;Syed and Chinthala, 2015;Chen et al., 2016). A transcription regulatory protein (CadC) and ATPase type protein (CadA) from a Bacillus megateriumstrain NBRC 114811 and its resistance to Zn, Cu, Cd and Pb has also been reported (Kumari et al., 2021). ...
An effluent sample collected from a textile dyeing factory was screened to isolate metal resistant endogenous bacteria using standard microbiology techniques. A bacterium with the highest metal resistance was characterized by 16S rRNA gene sequencing and the bacterial genome was screened for any possible metal resistant genes using the Polymerase Chain Reaction (PCR). The bioremoval ability of the isolate was evaluated using a multi-metal contaminated industrial effluent. Metal immobilisation was assayed using Scanning Electron Microscopy and Energy-Dispersive X-ray (SEM-EDX) analysis. An isolate (strain TWSL_5) was characterized as a Bacillus cereus strain. MICs of the strain TWSL_5 were found to be 75 mg/L (copper), 50 mg/L (cadmium) and 1000 mg/L (lead). The MIC for lead is among the highest reported for the species, B. cereus. The strain TWSL_5 showed a higher metal removal activity (p<0.001) for copper (93.13±0.17%) and lead (85±1.4%) in spiked cultures. The bacterium could successfully remove lead (100±0.00%), iron (68.22±0.07%), zinc (88.71±0.62%) and chromium (100±0.00%) from an effluent in 7 days of incubation at pH 6 and an insoluble black solid formed was detected as iron by SEM-EDX. The presence of copA in the genome of TWSL_5 was confirmed by PCR followed by sequence analysis. The presence of a gene involved in heavy metal resistance (copA), metal immobilization ability and the multi-metal removal activity of TWSL_5 in both spiked cultures and in an industrial effluent, indicates its potential to be used in metal bioremediation of industrial wastewater.
