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Role of actinomycetes in bioactive and nanoparticle synthesis
Abstract
Actinomycetes commonly known as filamentous, Gram positive, spore forming actinobacteria and considered as connecting between the bacteria and fungi. Currently from last few decades actinomycetes used as a resource for the production of bioactive compounds and nanoparticles. Besides these actinomycetes are also rich sources of various enzyme having industrial importance. The bioactive compounds contain a range of primary or secondary metabolites that help in growth and maintaince of plant as well as human beings. Many bioactive compounds have diverse range of pharmaceutical properties like antibiotics, antimicrobials, antibiotics etc. Now days actinomycetes have also being used in the nanotechnology for the synthesis of various nanoparticles, that are used in sustainable agricultural processes as nano-fertlizers or biocontrol agents. In this chapter we summarize the role of actinomycetes in the sustainable agriculture, or their role in bioactive compound production or in the field of nanotechnology.
... Broadly, Aspergillus species and Candida albicans fungi [130] were utilized to produce ZnO NPs and most of these nanoparticles were reported to be spherical in shape. Actinomycetes are less utilized microorganisms for producing metal nanoparticles [131]. On the other hand, Actinomycetes appear to be viable candidates for the intracellular and extracellular synthesis of metal nanoparticles [132]. ...
... It is possible for nanoparticles of a certain size to easily enter the tumour interstitial space while being passively held by this localized imbalance, increasing the therapeutic potential. Recent studies have demonstrated the value of ZnO NPs encapsulated in polymethyl methacrylate for identifying the low-abundance biomarkers [131]. ...
Nanotechnology focuses on the development and application of materials with nanoscale dimensions. Zinc oxide nanoparticles are theones that have the potential to play an important role in different fields like antimicrobial, antioxidant, photocatalysis, agriculture, rubber, textile and environmental remediation because of their cost-effectiveness, easy to use and environmentally safe nature. ZnO nanoparticles have recently been the subject of research due to their broad band width and strong excitation-binding energy. ZnO nanoparticles are synthesized using a variety of physical, chemical and biological processes. Green techniques involving plants, fungi, bacteria and algae have evolved to avoid the rapid release of toxic substances and use of extreme environments for the physical and chemical production of ZnO nanoparticles. This review article aims to summarize the recent work on the formation of ZnO nanoparticles and their applications in various fields.
... All these factors intrigued an increasing need to develop alternative synthesis techniques that are efficient as well as inexpensive, and non-toxic. This led to exceeding research involving biological methods [42,43] that employ unicellular and multicellular biological entities such as bacteria [44], actinomycetes [45,46], viruses [47,48] yeasts [49], fungi [50,51], algae [52,53] and plants [54][55][56][57] for the synthesis of nanoparticles. Amongst these, plant-based biosynthesis is now regarded as a gold standard owing to its ease of use and the diversity of plants [58]. ...
Nanotechnology and biogenic synthesis of metal nanoparticles using plants have attracted immense attention recently owing to their beneficial applications. Ultrasonication technique was employed for the rapid one-step phytochemical synthesis of AuNPs from the extracts of Nothapodytes foetida leaves. The N. foetida AuNPs exhibited the characteristic UV absorption peak at 524 nm. Several analytical techniques, including FESEM, TEM, XRD, FTIR, TGA, ICP and zeta potential analysis, were performed for their effective characterization. These analyses revealed highly stable (– 60.7 mV) crystalline AuNPs, majorly spherical, ranging between 5 and 30 nm. Furthermore, CCD-RSM was incorporated to determine the influence of the temperature, N. foetida leaf extract and HAuCl4 concentration on the synthesis of AuNPs. LC-MS revealed the phytocompounds that contributed to AuNP synthesis which was subsequently confirmed by TPC and TFC reduction. Potent radical scavenging ability accompanied by the antibacterial activity of the AuNPs was also evaluated. Importantly, AuNPs also reduced the cell viability of MG63 and A549 cell lines, exhibiting significant anticancer activity along with appreciable wound-healing properties. These findings suggest that these AuNPs possess tremendous biological potentialities and can be bio-prospected further for various multidisciplinary applications.
... Actinomycetes are Gram-positive, aerobic entities [66] with bacteria-like cell wall composition [67] and fungus-like branched filamentous growth [68,69] found both in soil and aquatic conditions. There is comparatively a limited number of studies synthesizing AgNPs via actinomycetes. ...
Owing to the unique property of large surface area/volume of nanoparticles, scientific developments have revolutionized the fields of nanotechnology. Nanoparticles can be synthesized through physical, chemical, and biological routes, where biologically synthesized nanoparticles are also referred to as biogenic-synthesized nanoparticles or bionanoparticles. Bionanoparticles exploit the inherent reducing property of biological entities to develop cost-effective, non-toxic, time-efficient, sustainable, and stable nanosized particles. There is a wide array of biomedical focus on metallic nanoparticles, especially silver nanoparticles, due to their distinctive physiochemical properties making them a suitable therapeutic molecule carrier. This article aims to provide a broad insight into the various classes of living organisms that can be exploited for the development of silver nanoparticles, and elaboratively review the interdisciplinary biomedical applications of biogenically synthesized silver nanoparticles in health and life sciences domains.
... The dried powder derived from ground rhizome of the plant Curcuma longa Linn., commonly called as haldi in Hindi and turmeric in English has been used as major source of folk remedy, diet spice, beauty aid and as a dye since ancient time and it continues today [28]. Turmeric has a long tradition of use in the Indian holistic medical system, Ayurveda as a part of medicine to treat many diseases, such as, gas, cough, colic, sinusitis, toothaches, inflammations, digestive disorder, chest pains, menstrual difficulties, muscular disorders, hepatic disorders, biliary disorders etc [29][30][31][32][33][34]. Moreover, it contains lots of bioactive polyphenolic compounds, such as, essential oils, phenolic acids, curcuminoids and flavonoids etc. (Fig. 1) [35]. ...
Biosynthesized noble metal nanoparticles have been of recent interest due to their broad implications in the future biomedicinal field. We have synthesized silver nanoparticle using turmeric-extract and its major component curcumin as reducing and stabilizing agents. Further, we have investigated the protein-NPs interaction focusing the inspection of the role of biosynthesized AgNPs on any conformational changes of the protein, binding and thermodynamic parameters using spectroscopic techniques. Fluorescence quenching studies revealed that both CUR-AgNPs and TUR-AgNPs have moderate binding affinities (∼104 M-1) towards human serum albumin (HSA) and static quenching mechanism was involved in the binding. Estimated thermodynamic parameters indicate the involvement of hydrophobic forces in the binding processes. The surface charge potential of the biosynthesized AgNPs became more negative upon complexation with HSA as observed from Zeta potential measurements. Antibacterial efficacies of the biosynthesized AgNPs were evaluated against Escherichia coli (gram-negative) and Enterococcus faecalis (gram-positive) bacterial strains. The AgNPs were found to destroy the cancer (HeLa) cell lines in vitro. The overall findings of our study successfully outline the detailed insight of the protein corona formation by biocompatible AgNPs and their biological applications concerning the future scope in the biomedicinal field.
... Actinomycetes have been used as a source for the synthesis of bioactive compounds and nanoparticles in recent decades. Actinomycetes are now used in nanotechnology to synthesize a variety of nanoparticles that can be used as nanofertilizers or biocontrol agents in sustainable agricultural processes (Gupta et al., 2019). Actinomycetes are excellent sources for the biosynthesis of nanoparticles because of their different secreted secondary metabolites. ...
... e biogenic fabrication of the nanoscale particles is preferable to physical and chemical processes due to its properties of energy efficiency, ease of scaling-up, low cost, low toxicity, and biocompatibility. erefore, biogenic nanoparticles can be safely exploited in many biological applications [20,21]. ...
Plant growth and development rely on various factors, including mineral nutrients. Some are macronutrients like nitrogen, phosphorus, and potassium, whereas some are micronutrients like iron, magnesium, zinc, and a few vitamins. This experimental attempt was to check the stimulatory effect of zinc nanoparticles on pulse plant growth. The study was conducted on the green synthesis of zinc oxide nanoparticles using Coriandrum sativum leaves extract. The characterization of zinc oxide nanoparticles was studied using the X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope technique (TEM). The effect of zinc oxide nanoparticles as a fertilizer on pulses plant (Bengal gram, Turkish gram, and green grams) was studied in vitro. The seed germination rate, length of root and shoot, fresh weight, dry weight, and protein and chlorophyll content were measured in different media for assessment of zinc oxide nanoparticle’s growth stimulatory effects. The green synthesis of zinc oxide nanoparticles was confirmed with a size around 100 nm by transmission microscope technique. The germination rate of plants was 100% in MS media and MS media + nanoparticles. The present study found that the root length, shoot length, and weight were higher in MS media + nanoparticles followed by MS media, MS media only with nanoparticles, and MS media without zinc, respectively. It is found that the zinc oxide nanoparticles support seed germination and plant growth and also increase the protein and chlorophyll content. Significantly enhanced growth and development were evident in green gram and Turkish gram compared to that in Bengal gram in media treated with zinc oxide nanoparticles. The protein estimation results showed that the content was higher after 7 days in plants of Bengal gram (1.23 mg/ml), Turkish gram (1.19 mg/ml), and green gram (1.26 mg/ml) than that in roots and shoots. The application of MS media + ZnO nanoparticles results showed that chlorophyll content 12.6 mg/l was observed in other applications in the plant’s seedlings. In contrast, the absence of zinc decreases the germination rate, plant growth, chlorophyll, and protein content. This study confirms that the green synthesis of zinc oxide nanoparticles assessed from Coriandrum sativum leaves holds implication and should function as an active biofertilizer.
... Biogenic synthesis of metal nanoparticles has been demonstrated using bacteria, fungus, algae, actinomycetes, plants, and other organisms. Actinomycetes are one of the less well-known microorganisms employed in producing metal nanoparticles [152]. However, reports suggest that actinomycetes are effective candidates for the intracellular and extracellular synthesis of metal nanoparticles [153]. ...
Nanotechnology has infiltrated all sectors due to its unique and evident impacts, which give the scientific community numerous breakthroughs in the medical, agricultural, and other domains. Nanomaterials (NMs) have risen to prominence in technological breakthroughs due to their adjustable physical, chemical, and biological characteristics and superior performance over bulk equivalents. NMs are divided into many categories based on size, composition, capping agents, form, and origin. The capacity to forecast NMs' unique features raises the value of each categorization. As the manufacturing of NMs and industrial uses grow, so does their demand. The purpose of this review is to compare synthetic and naturally occurring nanoparticles and nanostructured materials to determine their nanoscale characteristics and to identify particular knowledge gaps related to the environmental application of nanoparticles and nanostructured materials. The paper review includes an overview of NMs' history and classifications and the many nanoparticles and nanostructured materials sources, both natural and manufactured. Furthermore, the many applications for nanoparticles and nanostructured materials.
... Nanoparticles (NPs) can be biosynthesized by living organisms such as bacteria, fungi, and plant extracts [1][2][3]. Biologically synthesized NPs, or biogenic nanoparticles, provide a green alternative to existing chemical methods of NP synthesis, and can be less toxic, less energy-intensive to produce, and result in lower levels of hazardous by-products that have environmentally "Nano-Bio Revolution" in the field of nano-enabled biocompatible NPs synthesis technologies. Metallic NPs are an important class of nanoparticles with a wide range of potential applications. ...
Proteins are known to play important roles in the biosynthesis of metallic nanoparticles (NPs), which are biological substitutes for conventionally used chemical capping and stabilizing agents. When a pristine nanoparticle comes in contact with a biological media or system, a bimolecular layer is formed on the surface of the nanoparticle and is primarily composed of proteins. The role of proteins in the biosynthesis and further uptake, translocation, and bio-recognition of nanoparticles is documented in the literature. But, a complete understanding has not been achieved concerning the mechanism for protein-mediated nanoparticle biosynthesis and the role proteins play in the interaction and recognition of nanoparticles, aiding its uptake and assimilation into the biological system. This review critically evaluates the knowledge and gaps in the protein-mediated biosynthesis of nanoparticles. In particular, we review the role of proteins in multiple facets of metallic nanoparticle biosynthesis, the interaction of proteins with metallic nanoparticles for recognition and interaction with cells, and the toxic potential of protein-nanoparticle complexes when presented to the cell.
... The biosynthesized AgNPs exhibited uniform spherical shape with slight aggregation associated with bioorganic molecules which eventually led to delaying their volatilization, stabilization and functionalization as implied by EDX, FT-IR and TGA. Such results matched those reported by [14,[56][57][58]. Upon recruitment as antimicrobial agent, AgNPs displayed considerable and significant clear zones of inhibition in all examined pathogens, which were deemed good and effective as long as the zone exceeded 1 mm as highlighted by [59]. ...
Lake Mariout is one of the polluted coastal marine ecosystems in Egypt which is considered to be a reservoir of serious effluents from different anthropogenic activities. Such selective pressure enforces indigenous microbial populations to acquire new advantageous themes. Thus, in this study, two Streptomyces strains were screened, from Lake Mariout’s sediment for bioreduction of 5 mM AgNO3. Both strains were identified molecularly; their biochemical and physiological characterization revealed their ability to secrete bioactive metabolites with antagonistic activity. The cultural and incubation conditions influencing AgNPs productivity were evaluated. Subsequently, the physicochemical properties of the biofabricated AgNPs were pursued. UV-Vis spectroscopy detected surface plasmon resonance at range 458–422 nm. XRD indicated crystalline, pure, face-centered cubic AgNPs; EDX demonstrated strong silver signal at 3.5 keV. Besides, FT-IR and TGA analysis unveiled self-stabilization and functionalization of AgNPs by bioorganic molecules. However, electron microscopy micrographs depicted numerous uniform spherical AgNPs (1.17–13.3 nm). Potent bactericidal and fungicide activity were recorded by zone of inhibition assay at 50 μg/mL. Further, the antibiofilm activity was exerted in a dose-dependent manner. Moreover, the conjugation of AgNPs with the crude bioactive metabolites of both bionanofactories ameliorated the antimicrobial potency, reflecting a synergistic efficiency versus examined pathogens (free-living and biofilm).
... Green chemistry is the design, development, and replacement of harsh chemical products and processes that are non-toxic, clean, cost-effective and environmentally benign [5][6][7]. Recently, a tremendous attention was paid for green synthesis of metal nanoparticles by using several biological entities such as bacteria [8], fungi [9], actinomycetes [10], yeast [11], algae [12] and plants [13][14][15]. Because of their ecofriendly, cheap and feasible schemes biological synthesis was fixed to be most favored route among other traditional methods. ...
This research demonstrates biosynthesis of three different silver nanoparticles (AgNPs)by using tulsi extract and two of its flavonoids, quercetin (QUE) and luteolin (LUT) as reducing agents. The surface morphology, composition and crystallinity are characterized by different techniques. The biomedicinal applicability of synthesized AgNPs were assessed by determining anti-bacterial activity against selected gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacterial strains. Interaction of biocompatible AgNPs with the HEWL lead to the formation of protein corona. In this regard, the interactions of the synthesized AgNPs with hen egg white lysozyme (HEWL) were investigated by using multi-spectroscopic techniques. Fluorescence studies revealed that upon addition of these AgNPs, quenching of protein fluorescence occurs and it quenching mechanism was static in nature, while the binding affinity of QUE-AgNPs was remarkably higher than Tulsi-AgNPs and LUT-AgNPs. The binding interaction of HEWL with these biocompatible AgNPs is found to be spontaneous and the respective binding distance obtained by using FRET calculations confirms the possibility of non-radiative energy transfer from HEWL to nanoparticles. As indicated by synchronous fluorescence study, a slight decrease in polarity of Trp microenvironment was induced due to the binding with Tulsi- AgNPs while the LUT-AgNPs showed an opposite effect, but the QUE-AgNPs causes no such impacts on the Trp microenvironment. This study provides an informational insight into the polyphenol mediated synthesis of AgNPs, their anti-bacterial activities and the binding interaction between HEWL and biosynthesized AgNPs indicating a new application of nanoparticles in the field of drug transportation and metabolism.
... Actinomycetes are also a source of formulates for the management of fungal plant diseases. However, only a few studies have evaluated CFSs or metabolites obtainable by these microorganisms [124] and dealing exclusively with the Streptomyces genus [112][113][114][115][116]119]. Noteworthy are the studies of Kaur et al. and Jacob et al., who reported good in planta biocontrol capabilities of CFS on Fusarium moniliforme on S. lycopersicum [117] and Sclerotium rolfsii on Arachis hypogaea [118], respectively. ...
Plant growth-promoting bacteria (PGPB) afford plants several advantages (i.e., improvement of nutrient acquisition, growth, and development; induction of abiotic and biotic stress tolerance). Numerous PGPB strains have been isolated and studied over the years. However, only a few of them are available on the market, mainly due to the failed bacterial survival within the formulations and after application inside agroecosystems. PGPB strains with these challenging limitations can be used for the formulation of cell-free supernatants (CFSs), broth cultures processed through several mechanical and physical processes for cell removal. In the scientific literature there are diverse reviews and updates on PGPB in agriculture. However, no review deals with CFSs and the CFS metabolites obtainable by PGPB. The main objective of this review is to provide useful information for future research on CFSs as biostimulant and biocontrol agents in sustainable agriculture. Studies on CFS agricultural applications, both for biostimulant and biocontrol applications, have been reviewed, presenting limitations and advantages. Among the 109 articles selected and examined, the Bacillus genus seems to be the most promising due to the numerous articles that support its biostimulant and biocontrol potentialities. The present review underlines that research about this topic needs to be encouraged; evidence so far obtained has demonstrated that PGPB could be a valid source of secondary metabolites useful in sustainable agriculture.
... The biogenic fabrication of the nanoscale particles is preferable to physical and chemical processes, due to its properties of energy efficiency, ease of scaling-up, low coast, low toxicity, and biocompatibility. Therefore, biogenic nanoparticles can be safely exploited in many biological applications [37]. The actinomycetes, particularly Streptomyces, are some of the best candidates for the large-scale biological fabrication of nano-sized materials, as a result of its cost-effectiveness due to its rapid growth, high biomass production, and environmental friendliness [38]. ...
An endophytic strain of Streptomyces antimycoticus L-1 was isolated from healthy medicinal plant leaves of Mentha longifolia L. and used for the green synthesis of silver nanoparticles (Ag-NPs), through the use of secreted enzymes and proteins. UV-vis spectroscopy, Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) analyses of the Ag-NPs were carried out. The XRD, TEM, and FT-IR analysis results demonstrated the successful biosynthesis of crystalline, spherical Ag-NPs with a particle size of 13-40 nm. Further, the stability of the Ag-NPs was assessed by detecting the surface Plasmon resonance (SPR) at 415 nm for one month or by measuring the NPs surface charge (−19.2 mV) by zeta potential analysis (ζ). The green-synthesized Ag-NPs exhibited broad-spectrum antibacterial activity at different concentrations (6.25-100 ppm) against the pathogens Staphylococcus aureus, Bacillus subtilis Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium with a clear inhibition zone ranging from (9.5 ± 0.4) nm to (21.7 ± 1.0) mm. Furthermore, the green-synthesized Ag-NPs displayed high efficacy against the Caco-2 cancerous cell line (the half maximal inhibitory concentration (IC 50) = 5.7 ± 0.2 ppm). With respect to antibacterial and in-vitro cytotoxicity analyses, the Ag-NPs concentration of 100 ppm was selected as a safe dose for loading onto cotton fabrics. The scanning electron microscopy connected with energy-dispersive X-ray spectroscopy (SEM-EDX) for the nano-finished fabrics showed the distribution of Ag-NPs as 2% of the total fabric elements. Moreover, the nano-finished fabrics exhibited more activity against pathogenic Gram-positive and Gram-negative bacteria, even after 10 washing cycles, indicating the stability of the treated fabrics.
In recent times, the use of nanomaterials has gained prominence in the fields of agriculture, biological science, electronics, and medicine owing to their numerous applications. Their unique characteristics, such as high surface/volume ratio, specific structures, and dimensions that are similar to those of biomolecules, provide special features for biomedical and therapeutic applications. It is well known that algae, bacteria, and fungi can take metals from their surroundings and transform them into elemental nanoparticles, which can then be accumulated or released. Actinomycetes, as green nanofactories, have been regarded as an emerging field for research to produce low-cost, high-quality approaches for producing sustainable useful products with numerous applications. The distinctiveness of biologically active actinomycetes has drawn the attention of experts all around the world to better understand their possibility as effective nanofactories. As a dominant microbial phylum, actinomycetes are helpful for the breakdown and transformation of organic and inorganic substrates and can also synthesize economically viable proteins, enzymes, and antibiotics. Antibiotics produced by these organisms have been utilized in almost every medical intervention and are now known to facilitate the production of nanoparticles with preferred surface and size attributes. Actinomycetes-derived nanoparticles have also been extensively studied for a wide range of applications related to biomedical sciences. This chapter provides an overview of the synthesis of nanomaterials from actinomycetes, characterization techniques, and various biomedical and therapeutic applications. In addition, the challenges pertaining to toxicity studies associated with the use and synthesis of biogenic metal nanoparticles are discussed.
Currently, environmental pollution, which could be attributed to both direct and indirect sources, is one of the top-ranked issues worldwide. It is the uncontrolled and less manageable use of natural resources by human beings to contaminate various parts of the natural ecosystem including soil, air, and water, which may create a hostile environment. To create clean and sustainable working conditions, environmental remediation and restoration using various advanced physico-chemical techniques have now become a global focus. Of the various classes of environmental pollution, water pollution has been taken as the most serious disaster that causes a significant number of deaths around the globe. The contamination of water is mainly contributed to by the advancement in urbanization, mining, improvement and development of industrialization, and growth of the world population. In the previous decades, immense physico-chemical wastewater remediation protocols have been extensively explored. However, those remediation techniques of polluted water have several drawbacks and limitations. Recently, the elaboration of efficient and operative nanomaterials synthesized via green methods has been considered the most advanced alternative for wastewater nanoremediation techniques. Various classes of green alternative capping and reducing agents such as different parts of green plants, bacteria (Gram-positive and -negative species), fungi, algae, and even viruses are highly employed during the synthesis of numerous nanomaterials such as metal oxide nanoparticles (M-MONPs), decorated and doped nanoparticles (D-NPs), and nanocomposites (NCs). In this book chapter, the synthesis of various grades of nanomaterials, including M-MONPs, D-NPs, and NCs in the area of green synthesis via green methods are extensively addressed. The synthesized green nanomaterials would then be characterized using dynamic light scattering, Fourier transform infrared, scanning electron microscopy-energy-dispersive spectroscopy, transmission electron microscopy-high resolution transmission electron microscopy with selected area electron diffraction, thermogravimetric analysis/differential thermal analysis, X-ray diffraction, and ultraviolet visible diffuse reflectance spectroscopytechniques to obtain their physico-chemical properties. The applications of those green nanomaterials as cost effective and recyclable alternative catalysts and high surface area adsorbents for wastewater remediation are extensively described. Controlling factors and parameters interfering during the remediation of polluted water using green nanomaterials are also well addressed.KeywordsEnvironmental remediationNanomaterialsGreen synthesisWastewater treatment
Because of anthropogenic activities and urbanization, planet earth is becoming polluted in both developing and developed countries, thus becoming a global concern. The pollutants and contaminants released from industries, agricultural practices, and other source have become most hazardous to humans and are putting humans at high health risks. Nanotechnology, an emerging field, produces nanoscale materials that are effective in bioremediation. The practice of synthesizing nanoparticles (NPs) and nanomaterials (NMs) from physical and chemical methods is losing steam because of its adverse effects on environment. These methods have their own limitations in the means of toxicity and stress to the environment. Green chemistry, the new discipline in combination with nanotechnology, produces bio-based nanoparticles by using plants and microorganisms as chief sources. The nanoparticles/nanomaterials synthesized from this method show minimum toxicity and are cost-effective and generally nonhazardous. Nanoremediation is a novel strategy that reduces the burden of environmental pollution by detoxification, reducing heavy metals to zero-valent metals and transforming contaminants to clean up the environment. This chapter includes the protocols generally followed to synthesize biogenic nanoparticles and their in situ applications in the remediation of contaminated environments, with particular emphasis on the microbe-mediated aspects of nanotechnology.
The alarming impact of antibiotic resistance sparked the quest for complementary treatments to overcome the confrontation over resistant pathogens. Metallic nanoparticles, especially silver nanoparticles (Ag NPs) have gained a much attention because of their remarkable biological characteristics. Moreover, their medicinal properties can be enhanced by preparing the composites with other materials. This article delves a comprehensive review of biosynthesis route for Ag NPs and their nanocomposites (NCs) with in-depth mechanism, methods and favorable experimental parameters. Comprehensive biological features Ag NPs such as antibacterial, antiviral, antifungal have been examined, with a focus on their potential uses in biomedicine and diagnostics has also been discussed. Additionally, we have also explored the hitches and potential outcomes of biosynthesis of Ag NPs in biomedical filed.
Silver nanoparticles represent a scientific response to increasing resistance of microbes to conventional antibiotics. Methods of green synthesis represent an eco-friendly and economical approach for silver nanoparticles preparation. Actinomycetes, as specific microorganisms, serve as a good source of molecules therapeutically used for treatment of various microbial infections. Their ability to produce bioactive compounds is leading to their use as producers of nanoparticles of metal ions. The synthesis may be conducted intracellularly or extracellularly using specific biochemical mechanisms. This chapter deals with biogenic synthesis of silver nanoparticles using actinomycetes and biological activity studies of prepared silver nanoparticles.
Bioresource-based green synthesis of metallic nanoparticles has received considerable attention from researchers across the world due to its discriminable properties. This leads to the development of various ways of producing metallic nanoparticles using different physical and chemical methods. Yet, the significant drawback of these strategies is that they stay costly and include the utilization of unsafe synthetic substances. Along these lines, there is a developing concern for creating environmentally friendly and sustainable practices for the synthesis of the nanoparticle. This method mainly focused on the biological approach by using green sources like plants, different plant parts, and microorganisms such as bacteria, fungi, actinomycetes, yeast, and algae. This chapter focuses on the mechanism of nanoparticles synthesized by different microorganism like bacteria, fungi, actinomycetes, and yeast and also the use of various microbes for the synthesis of nanoparticles such as silver, gold, uranium oxide, cadmium sulfide, lanthanum, platinum, palladium, zinc oxide, zirconium, etc. These microbes provide a comprehensive environment for the biosynthesis of nanoparticles using their metabolites such as enzymes and other biomaterials, inside its cells. The microorganisms adopted both extracellular and intracellular synthesis mechanisms to synthesize metal and metal oxide nanoparticles successfully. These nanoparticles are highly useful, environmentally friendly with a lot of applications in agriculture and biomedical fields.
Currently postharvest loss of food commodities is a global challenge and it has been estimated that
nearly 30%–50% of the fresh products were lost during the postharvest storage due to pathogenic attack,
improper storage, transportation, or packaging. The pathogenic attack during postharvest storage is
considered as the prime factor for postharvest loss. Conventionally, breeders frequently utilized chem-
ical pesticides or fungicides to manage pathogenic attack and enhance the shelf life of food products.
However, inappropriate and continuous use of chemical pesticides lead to adverse impacts such as chemical residue, low-quality product, and environmental contaminants, or phytopathogens resistance.
Thus, there is a need to search for an alternative, that must be eco-friendly, cost-effective, and free from chemical residue. The microbial antagonism is an emerging approach and is broadly utilized in man-aging the growth of pathogens during pre- or postharvest storage. This chapter summarizes the latest approach and mode of action of microbial antagonistic in managing the pathogens of fresh products
during postharvest storage.
The biosynthesis of nanoparticles by microorganisms especially endophytic species isolated from medicinal plant are the prime concern of researchers. In the present study, a novel, non-toxic, eco-friendly copper nanoparticles was biosynthesized by endophytic actinomycetes isolate Ca-1 and optimization processes have been endeavored. The endophytic actinomycete Streptomyces capillispiralis Ca-1, was isolated from healthy medicinal plant (Convolvulus arvensis) (L.) collected from Bahariya Oasis-Giza Governorate e Egypt. The isolate was identified by morphological, cultural and molecular identification techniques. The biosynthesis of CuNPs is confirmed by gradual change of biomass filtrate color from light blue into greenish brown color and characterized by an observation of a characteristic absorption peak by UV-Vis spectroscopy at 600 nm. Also, a spherical-monodispersed shaped CuNPs with particle size of 3.6 e59 nm were observed by Transmission Electron Microscopy (TEM). In addition, X-ray diffraction (XRD) exhibited pattern peaks corresponding to 110, 111, 200, 220, 311 and 222 planes, respectively that assigned to face centered cubic forms of metallic copper (JCPDS 04e0836). While FTIR results confirmed the occurrence of bioactive functional groups that are responsible for formation of CuNPs. Moreover, the biosynthesized CuNPs showed various biomedical applications against infectious microorganisms, biocontrol of phytopathogenic fungi and health nasty insects that represent the hopeful uses of copper nanoparticles to be applied as a unique approach to manage these healths threatening problems.
A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDAX), and X-ray Powder Diffraction (XRD), and broth micro dilution techniques were employed for the determination of minimum inhibitory concentrations (MIC) values. The synthesized NP was authenticated by alterations in color and wavelength scanning. HRSEM and TEM analysis confirmed that the size of the NP ranged from 10 to 17 nm and that it was spherical in shape. In addition, the FTIR spectrum revealed a variation in the band values from 500 to 3300 cm−1 respectively. Rietveld refinement analysis of the XRD data confirmed the size of the NP, which coincided with the results of the TEM analysis. In addition, the Riveted refinement analysis supported the TEM data. The NP documented significant activity against the wound infection microbial strains, such as Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus. Gram negative bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli revealed MIC values of 0.039, 0.078, and 0.152 mg/mL, respectively. The promising activity of NP towards extended-spectrum beta-lactamases E.coli, drug resistant Acinetobacter baumannii, and multidrug resistant S. aureus (at 0.018, 0.039, and 0.039 mg/mL, respectively) was advantageous. Overall, NP that were obtained from the novel Streptomyces sp. Al-Dhabi-87, with its promising antimicrobial activity towards the drug resistant pathogens, would be useful for healing infectious diseases.
Background:
Selenium (Se) is an essential trace element in living systems. Microorganisms play a pivotal role in the selenium cycle both in life and in environment. Different bacterial strains are able to reduce Se(IV) (selenite) and (or) Se(VI) (selenate) to less toxic Se(0) with the formation of Se nanoparticles (SeNPs). The biogenic SeNPs have exhibited promising application prospects in medicine, biosensors and environmental remediation. These microorganisms might be explored as potential biofactories for synthesis of metal(loid) nanoparticles.
Results:
A strictly aerobic, branched actinomycete strain, ES2-5, was isolated from a selenium mining soil in southwest China, identified as Streptomyces sp. based on 16S rRNA gene sequence, physiologic and morphologic characteristics. Both SEM and TEM-EDX analysis showed that Se(IV) was reduced to Se(0) with the formation of SeNPs as a linear chain in the cytoplasm. The sizes of the SeNPs were in the range of 50-500 nm. The cellular concentration of glutathione per biomass decreased along with Se(IV) reduction, and no SeNPs were observed in different sub-cellular fractions in presence of NADPH or NADH as an electron donor, indicating glutathione is most possibly involved in vivo Se(IV) reduction. Strain ES2-5 was resistant to some heavy metal(loid)s such as Se(IV), Cr(VI) and Zn(II) with minimal inhibitory concentration of 50, 80 and 1.5 mM, respectively.
Conclusions:
The reducing mechanism of Se(IV) to elemental SeNPs under aerobic condition was investigated in a filamentous strain of Streptomyces. Se(IV) reduction is mediated by glutathione and then SeNPs synthesis happens inside of the cells. The SeNPs are released via hypha lysis or fragmentation. It would be very useful in Se bioremediation if Streptomyces sp. ES2-5 is applied to the contaminated site because of its ability of spore reproduction, Se(IV) reduction, and adaptation in soil.
Streptomyces lomondensis S015 synthesizes the broad-spectrum phenazine antibiotic lomofungin. Whole genome sequencing of this strain revealed a genomic locus consisting of 23 open reading frames that includes the core phenazine biosynthesis gene cluster lphzGFEDCB. lomo10, encoding a putative flavin-dependent monooxygenase, was also identified in this locus. Inactivation of lomo10 by in-frame partial deletion resulted in the biosynthesis of a new phenazine metabolite, 1-carbomethoxy-6-formyl-4,9-dihydroxy-phenazine, along with the absence of lomofungin. This result suggests that lomo10 is responsible for the hydroxylation of lomofungin at its C-7 position. This is the first description of a phenazine hydroxylation gene in Streptomyces, and the results of this study lay the foundation for further investigation of phenazine metabolite biosynthesis in Streptomyces.
A total of 50 different actinomycete strains were recovered from farming soil samples collected from Manisa Province and its surrounding. These were then assessed for their antibacterial activity against four phytopathogenic and six pathogenic bacteria. Results indicated that 34% of all isolates are active against, at least, one of the test organisms; Agrobacterium tumefaciens, Erwinia amylovora, Pseudomonas viridiflova, Clavibacter michiganensis subsp. michiganensis, Bacillus subtilis ATTC 6633, Klebsiella pneumoniae ATTC 10031, Enterococcus feacalis ATCC 10541, Staphylococcus aureus ATCC 6538, Esherichia coli ATCC 29998 and Sarcina lutea ATCC 9341. According to antibacterial activity and spectrum broadness, seven of the isolates were selected and characterized by conventional methods. The unusual antibiotic profile of these isolates underlined their potential as a source of novel antibiotics.
Actinomycetes represent a high proportion of the soil microbial biomass and have the capacity to produce a wide variety of antibiotics and of extracellular enzymes. Several strains of actinomycetes have been found to protect plants against plant diseases. This review focuses on the potential of actinomycetes as (a) source of agroactive compounds, (b) plant growth promoting organisms, and (c) biocontrol tools of plant diseases. This review also addresses examples of biological control of fungal and bacterial plant pathogens by actinomycetes species which have already reached the market or are likely to be exploited commercially within the next few years.
Production of protein encapsulated silver nanoparticles (AgNPs) assisted by marine actinomycetes strain has been investigated. The selective isolate was identified as Streptomyces parvulus SSNP11 based on chemotaxonomic and 16S rRNA analysis. Maximum AgNPs production was observed within 24 h incubation time. The produced AgNPs are spherical in shape with monodispersive and crystalline in nature. The particle size distribution ranges from 1.66 to 11.68 nm with a mean size of 2.1 nm. The biosynthesized AgNPs revealed stretching vibrations of primary and secondary amines along with C–H and C–N, suggesting that metabolically produced proteins are involved in size regulation of reduced AgNPs. These particles possess an average negative zeta potential value of 81.5 mV with an electrophoretic mobility of 0.000628 cm2/Vs. The biosynthesized nanoparticles revealed antimicrobial property against gram negative as well as gram positive bacterial strains.
An actinomycete was isolated from mangrove soil collected from Nellore region of Andhra Pradesh, India, and screened for its ability to produce bioactive compounds. The cultural, morphological, and biochemical characters and 16S rRNA sequencing suggest that the isolated strain is Nocardiopsis alba. The bioactive compounds produced by this strain were purified by column chromatography. The in vitro antioxidant capacity of the isolated compounds (fractions) was estimated and fraction F2 showed very near values to the standard ascorbic acid. The potential fraction obtained by column chromatography was subjected to HPLC for further purification, then this purified fraction F2 was examined by FTIR, NMR, and mass spectroscopy to elucidate its chemical structure. By spectral data, the structure of the isolated compound was predicted as "(Z)-1-((1-hydroxypenta-2,4-dien-1-yl)oxy)anthracene-9,10-dione."
The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15 nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200 μ g/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine.
The gene cloning and recombination in the genus Streptomyces offers a good possibility to improve secondary metabolite production and creating new antibiotics. This type of genetic manipulation facilitated by the construction of different novel cloning vectors like plasmids, phages and transposable elements and also robust gene cloning methods. This review article describes some of these vectors and regulation of genes in Streptomyces.
The biological approach to synthesize metal nanoparticles is an important aspect of current nanotechnology research. Silver nanoparticles have been well-known for their inhibitory and antimicrobial effects. The ever-increasing antibiotic resistance in pathogenic and opportunistic microorganisms is a major threat to the health care industry. In the present investigation, silver nanoparticles have been successfully biosynthesized by Streptomyces sp JAR1. Biosynthesized silver nanoparticles were characterized by means of several analytical techniques including a UV-Visible spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction pattern analysis, and atomic force microscopy. An evaluation of the antimicrobial activity of silver nanoparticles (AgNPs) was carried out against clinically important pathogenic microorganisms. The metal nanoparticles were also evaluated for their combined effects with antibiotics against the clinical pathogens. The antibacterial activities of the antibiotics increased in the presence of the biologically synthesized AgNPs against the clinically important pathogens. The highest enhancing effect was observed for erythromycin against the test pathogens.
The taxonomic position of a bioactive marine isolate, strain DVR D4 was established using a polyphasic approach. The organism merits species status in the genus Amycolatopsis according to the chemical and phenotypic data. Phylogenetic analysis of the strain based on its 16S rDNA sequence shows that there was 100% pair-wise similarity and identity with no nucleotide gaps with the species Amycolatopsis alba strain DSM 44262. As the organism was distinguished with substantial differences in some of the phenotypic characteristics and other properties, it was proposed as a strain variety of Amycolatopsis alba and designated as Amycolatopsis alba var. nov DVR D4 (GenBank accession number of strain D4 is JN872327).
Emergence of drug resistance among pathogenic bacteria to currently available antibiotics has intensified the search for novel bioactive compounds from unexplored habitats. In the present study actinomycetes were isolated from two relatively unexplored and widely differing habitats such as mountain and wetlands and their ability to produce antibacterial substances were analyzed. Pure cultures of actinomycetes were identified by morphological and biochemical tests. Various genera of actinomycetes encountered included Nocardia, Pseudonocardia, Streptomyces, Nocardiopsis, Streptosporangium, Micromonospora, Rhodococcus, Actinosynnema, Nocardiodes, Kitasatosporia, Gordona, Intrasporangium and Streptoalloteichus. The frequency of occurrence of each genus was found to vary with sample. About 47% of wetland isolates and 33% of mountain isolates were identified as various species of Nocardia. The isolated strains differed among themselves in their ability to decompose proteins and amino acids and also in enzyme production potential. Antibiotic activities of these actinomycetes were evaluated against 12 test pathogenic bacteria by well diffusion method using agar wells in glycerol-yeast extract agar. About 95% of actinomycete isolates from wetland ecosystem and 75% of highland isolates suppressed in different degrees the growth of test pathogens. Relatively high antibacterial activity among these isolates underlined their potential as a source of novel antibiotics.
Three new cyclic heptapeptides, cyclomarins A−C (1−3), were isolated from extracts of a cultured marine bacterium collected in the vicinity of San Diego, CA. The major metabolite, cyclomarin A (1), contains three common and four unusual (or unique) amino acids. The structures of the new metabolites were determined using 1D and 2D NMR methods, and the stereochemistry was determined from an X-ray crystal structure of the diacetate derivative of 1. Cyclomarin A (1) displays significant antiinflammatory activity in both in vivo and in vitro assays.
The development of reliable, eco-friendly processes for the synthesis of nanoscale materials is an important aspect of nanotechnology. In this paper, we report on the use of an alkalotolerant actinomycete (Rhodococcus sp.) in the intracellular synthesis of gold nanoparticles of the dimension 5–15 nm. Electron microscopy analysis of thin sections of the gold actinomycete cells indicated that gold particles with good monodispersity were formed on the cell wall as well as on the cytospasmic membrane. The particles are more concentrated on the cytoplasmic membrane than on the cell wall, possibly due to reduction of the metal ions by enzymes present in the cell wall and on the cytoplasmic membrane. The metal ions were not toxic to the cells and the cells continued to multiply after biosynthesis of the gold nanoparticles.
Actinomycetes are virtually unlimited sources of novel compounds with many therapeutic applications and hold a prominent position due to their diversity and proven ability to produce novel bioactive compounds. There are more than 22,000 known microbial secondary metabolites, 70% of which are produced by actinomycetes, 20% from fungi, 7% from Bacillus spp. and 1-2% by other bacteria. Among the actinomycetes, streptomycetes group are considered economically important because out of the approximately more than 10,000 known antibiotics, 50-55% are produced by this genus. The ecological role of actinomycetes in the marine ecosystem is largely neglected and various assumptions meant there was little incentive to isolate marine strains for search and discovery of new drugs. The search for and discovery of rare and new actinomycetes is of significant interest to drug discovery due to a growing need for the development of new and potent therapeutic agents. Modern molecular technologies are adding strength to the target-directed search for detection and isolation of bioactive actinomycetes, and continued development of improved cultivation methods and molecular technologies for accessing the marine environment promises to provide access to this significant new source of chemical diversity with novel/rare actinomycetes including new species of previously reported actinomycetes.
There is little doubt that nanomaterials will play a key role in many technologies of the future. One key aspect of nanotechnology concerns the development of reliable experimental protocols for the synthesis of nanomaterials over a range of chemical compositions, sizes and high monodispersity. In the context of the current drive to develop green technologies in materials synthesis, this aspect of nanotechnology assumes considerable importance. An attractive possibility is to use micro-organisms in the synthesis of nanoparticles. In this article, we provide a brief overview of the research efforts worldwide on the use of micro-organisms in the biosynthesis of inorganic nanoparticles, with particular emphasis on the recent and exciting results obtained at the National Chemical Laboratory, Pune on the biosynthesis of noble-metal nanoparticles using fungi and actinomycete. Some of the challenges in this emerging approach are highlighted.
A literature survey covering more than twenty-three thousand bioactive microbial products including eight thousand antiinfectives demonstrated the increasing relevance of the so called ''rare'' actinomycetes as a source of new antibiotics. Past and present efforts in the isolation of rare actinomycetes have enriched the Biosearch Italia Strain Collection with more than twenty thousand strains, showing that, when selective isolation methods are developed and extensively applied, some genera, such as Actinomadura, Actinoplanes, Micromonospora, Microtetraspora, are not rare at all and can be recovered from many soil samples. The current focus is on the isolation of members of Streptosporangiaceae family, given their promising chemical diversity.
The aim of the present study was actinomycetes mediated biosynthesis of copper oxide nanoparticles (CuO NPs) and evaluation of its antibacterial activity against selected human and fish pathogens. The biosynthesized CuO NPs were characterized by UV–Visible (UV-Vis) spectroscopy. The presence of capping agents over the metal nanoparticles was confirmed by Fourier-Transform Infrared Spectroscopy (FT-IR). The crystalline nature of the CuO NPs was illustrated by X- Ray diffractometer (XRD). The average size of the biosynthesized CuO NPs from XRD and Transmission Electron Microscopy (TEM) was 61.7 nm. The XRD and Energy Dispersive X-Ray spectroscopy (EDX) suggests the purity of the biosynthesized CuO NPs. The morphology and size was viewed under Scanning Electron Microscopy (SEM). The Dynamic Light Scattering (DLS) results provided the zeta potential of − 31.1 mV which further confirmed the stability of the CuO NPs. The biosynthesized CuO NPs showed higher antibacterial activity (zone of inhibition) against various human and fish bacterial pathogens (Staphylococcus aureus, Bacillus cereus, Proteus mirabilis, Edwardsiella tarda, Aeromonas caviae, Aeromonas hydrophila and Vibrio anguillarum). The antibacterial activity of CuO NPs was significantly higher than the activity exhibited by cell free supernatant of actinomycetes. Among the pathogens tested B. cereus was more susceptible (25.3 mm) to biosynthesized CuO NPs. The antibacterial activity exhibited by the actinomycetes mediated biosynthesized CuO NPs suggests that it can combat both human as well as fish bacterial pathogens. To the best of our knowledge, this is the first report on actinomycetes mediated biosynthesis of CuO NPs.
This study aimed to green synthesis of silver nanoparticles (AgNPs) by cell lysates of actinobacterial strains isolated from Mersin soils. Also, free-radical scavenging potential, the inhibitory effect, and genotoxicity of synthesized AgNPs were investigated. As a result of the screening study, it was detected that cell lysate from isolate AOA21, which were classified in Streptomyces genus according to 16S rRNA gene sequences comparison, showed higher potential for AgNPs synthesis. The optimum pH, AgNO3 and cell lysate concentration for AgNPs synthesis were found to be pH 9.0, 1 mM AgNO3 and 2-fold diluted cell lysate, respectively. The FESEM analysis revealed that the size and shape of AgNPs were 35-60 nm and spherical. The x-ray diffraction patterns displayed typical peaks of crystalline AgNPs at 34.07°, 44.04°, 64.45°, 77.40° and 81.36°. The size of cubic crystalline AgNPs was found to be 9.35 nm. The FTIR analysis showed that the especially protein, peptide and amino acid component in the cell lysates of Streptomyces sp. AOA21 may be responsible in reduction of AgNO3 and stabilization of synthesized AgNPs. The MIC values of synthesized AgNPs for Bacillus cereus, Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus were found to be 8 μg ml⁻¹, 16 μg ml⁻¹, 16 μg ml⁻¹ and 32 μg ml⁻¹, respectively. Free-radical scavenging activity of synthesized AgNPs was 8.54%-55.58% at a concentration range of 800-2000 μg ml⁻¹. Furthermore, comet assay showed that synthesized AgNPs did not cause significant DNA damage in Saccharomyces cerevisiae at a concentration of 12.5 μg ml⁻¹ and 25 μg ml⁻¹.
Actinomycetes represent important microbial communities in the soils and inhabit very high proportion of soil microbial biomass that has the capacity to produce a wide range of high-value antibiotics, organic acids, phytohormones, extracellular enzymes, bioactive compounds, and secondary metabolites other than antimicrobials. Several strains of actinomycetes were found to promote plant growth directly and protect plants against phytopathogens and plant pests. The potential of this important microbial community for agricultural productivity is being greatly realized because they are a good source for agroactive compounds, plant growth-promoting substances, and biocontrol tools of the control of plant diseases. This chapter describes certain important aspects of actinomycetes in plant growth promotion and biological control.
Streptomyces griseoplanus SAI-25 isolated from rice rhizospheric soils with previously demonstrated insecticidal activity is currently characterized for silver nanoparticle synthesis using its extracellular extract. The synthesized particles showed the characteristic absorption spectra of silver nanoparticles at 413–417 nm. Spectral analysis by FTIR confirmed the presence of alcohols, amines, phenols and protein in the cell-free extracellular extract of SAI-25. These functional groups could have served dual roles in silver nanoparticle synthesis like reducing and stabilizing agents. Microscopic and spectroscopic analysis such as SEM, TEM, EDAX and XRD has provided the size, shape and composition of the synthesized nanoparticles. DLS and Zeta potential further confirms the size and characteristic negative charges of AgNPs respectively. The observed antifungal activity against charcoal rot pathogen Macrophomina phaseolina shows a base for the development of Streptomyces mediated nanoparticles in controlling this polyphagus pathogen and key role of biopesticides in improving agricultural economy.
Aims:
Presently, the effective antimicrobial agents have been limited by emergence of microbial strains with multi-drug resistance and biofilm formation potential. In the present study, we report remarkable antimicrobial activity of silver nanoparticles (AgNPs) synthesized from Streptomyces calidiresistens IF11 and IF17 strains, including inhibition of biofilm formation and synergistic effect of AgNPs and antibiotics against selected bacteria and yeasts. Cytotoxic effect of AgNPs on mammalian cell lines was also evaluated.
Methods and results:
Analysis of biosynthesized AgNPs by Fourier Transform Infrared spectroscopy and Transmission Electron Microscopy revealed their spherical shape, small size in the range of 5-50 and 5-20 nm, respectively as well as presence of capping agents. Study of antimicrobial activity of AgNPs against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Candida albicans and Malassezia furfur evaluated by Minimum Inhibitory Concentration (MIC) and Minimum Biocidal Concentration (MBC) assays revealed that MICs of AgNPs from IF11 and IF17 strains against bacteria and yeasts were found to be in the range of 16-128 and 8-256 μg ml-1 , while MBC of 48-192 and 32-256 μg ml-1 , respectively. AgNPs inhibited biofilm formation of microbial strains, which was tested by using crystal violet stain.The highest synergistic effect determined by Fractional Inhibitory Index of AgNPs with antibiotic (kanamycin or tetracycline) was found against S. aureus; while in case of yeasts, M. furfur showed highest sensitivity to AgNPs-ketoconazole combination (FIC=0.12). The cytotoxic activity of AgNPs towards HeLa and 3T3 cell lines was studied by MTT assay. The IC50 of AgNPs estimated against mouse fibroblasts was found to be 8.3 and 28.3 μg ml-1 and against HeLa cell line 28.5 and 53.8 μg ml-1 , respectively.
Conclusions:
It can be concluded that AgNPs synthesized from Streptomyces calidiresistens IF11 and IF17 strains have potential as an effective antimicrobial and cytotoxic agent, especially when used in combination with antibiotics/antifungal agents. This article is protected by copyright. All rights reserved.
Background:
Selenium nanoparticles (SeNPs) have gained significant importance because of its bioavailability, least toxicity, its interaction with proteins and its biocompatibility.
Objective:
In the present study, the extracellular synthesis of SeNPs was carried out by using culture supernatant of Streptomyces griseoruber, an Actinomycetes member isolated from the soil and cytotoxicity was tested on HT-29 cell line.
Methods:
Culture supernatant was mixed with 1mM sodium selenite for the biosynthesis of SeNPs. Characterisation of the synthesised SeNPs was done by UV-Visible spectrophotometer, FTIR, XRD, DLS and HR-TEM. The cytotoxicity of nanoparticles on HT-29 cell line was studied by MTT assay and with different staining procedure.
Results:
Bioreduction of SeNPs was confirmed by UV-Visible spectrophotometer that showed the peak at 575 nm. Size and distribution of the biosynthesised SeNPs were analysed by HR-TEM that showed the formation of particle size in the range of 100-250nm. The synthesised SeNPs showed good cytotoxic activity against HT-29 cell line with 40.5%, 33% and 23.7% of cell viability at 2μg/ ml, 4μg/ml and 30μg/ml concentration respectively.
Conclusion:
The present study reports the simple and eco-friendly synthesis of SeNPs that showed good cytotoxic activity against HT-29 cell line suggesting that biogenic SeNPs could be a potential chemotherapeutic agent.
Actinomycetes mediated biogenic synthesis of metal nanoparticles and their antimicrobial activities are well documented. Actinomycetes facilitate both intracellular and extracellular metal nanoparticles synthesis and are efficient candidates for the production of polydispersed, stable and ultra-small size metal nanoparticles. Secondary metabolites and new chemical entities derived from actinomycetes have not been extensively studied for the synthesis of metal/ metal oxide nanoparticles. The present review focuses on biogenic synthesis of metal nanoparticles from actinomycetes and the scope for exploring actinomycetes derived compounds (enzymes, organics acids and bioactive compounds) as metal and metal oxide reducing agents for the synthesis of desired nanoparticles. This review also focuses on challenges faced in the applications nanoparticles and the methods to synthesise biogenic metal nanoparticles with desired physiochemical properties such as ultra-small size, large surface to mass ratio, high reactivity etc. Methods to evade their toxicity and unique interactions with biological systems to improve their chance as an alternative therapeutic agent in medical and pharmaceutical industry are also discussed. This article is protected by copyright. All rights reserved.
Total thirteen Psychrophillic actinomycetes colonies were isolated from ice point region. Among these twelve are facultative psychrophile and the strain designated RH-2 is obligatory psychrophile. All the isolated Actinomycetes are morphologically distinct on the basis of pigment production, colour of spore, types of mycelium and biochemical properties. Thirteen isolates were assigned in to the genus Micromonspora (4) Streptomyces (5) Microployspora (1) Intrasporangium (1) Dactylsporangium (1) Plaromomospora (1). Among these, 12 isolates are capable to produce both aerial and substrate mycelium where the strain RH2 produce substrate mycelium only.
In the present study an attempt was made to evaluate the antimicrobial potential of culture filtrate of Streptomyces sp. VITBT7 and biologically synthesized silver nanoparticles using the culture filtrate of VITBT7. Actinomycetes isolates obtained from soil samples were screened for antimicrobial activity against selected fungal and bacterial pathogens by well diffusion method. The potential isolate was identified by molecular taxonomic characterization. The culture filtrate of the potential isolate was assessed for the synthesis of silver nanoparticles. The synthesized silver nanoparticles were characterized for surface plasma resonance (SPR) peak, shape and size distribution by TEM analysis. Out of 240 actinomycetes colonies recovered, 19 isolates showed mild to moderate antimicrobial activity and one potential isolate showed broad spectrum of activity against tested microbial pathogens with higher zone of inhibition against Pseudomonas aeruginosa and Aspergillus niger. The isolate was identified to be belonged to the genus Streptomyces and designated as Streptomyces sp. VITBT7 (accession number JX188053). The culture filtrate synthesized silver naoparticles (AgNPs) within 24 h. The biologically synthesized AgNPs showed SPR peak at 420 nm and were found to be spherical in shape with the size range of 20-70 nm. Synthesized AgNPs also exhibited antimicrobial activity against fungal and bacterial pathogens. Synthesized AgNPs by Streptomyces sp. VITBT7 could be used effectively to control fungal and bacterial pathogens. The secondary metabolites produced by Streptomyces sp. VITBT7 couldbe responsible for observed antimicrobial activity.
Nanotechnology is gaining tremendous attention in the present century due to its expected
impact on many important areas such as medicine, energy, electronics, and space industries.
In this context, actinobacterial biosynthesis of nanoparticles is a reliable, eco-friendly, and
important aspect of green chemistry approach that interconnects microbial biotechnology
and nanobiotechnology. Antibiotics produced by actinobacteria are popular in almost all the
therapeutic measures and it is known that these microbes are also helpful in the biosynthesis of
nanoparticles with good surface and size characteristics. In fact, actinobacteria are efficient
producers of nanoparticles that show a range of biological properties, namely, antibacterial,
antifungal, anticancer, anti-biofouling, anti-malarial, anti-parasitic, antioxidant, etc. This review
describes the potential use of the actinobacteria as the novel sources for the biosynthesis of
nanoparticles with improved biomedical applications.
Objectives:
The aim of the present study was to evaluate the anticandidal activity of biologically synthesized silver nanoparticles using the culture filtrate of Streptomyces sp.VITPK1.
Materials and methods:
Silver nanoparticles were synthesized using the culture filtrate of Streptomyces species isolated from brine spring located at Thoubal District, Manipur, India. The isolate was identified by molecular taxonomic characterization and designated as Streptomyces sp.VITPK1. The synthesized silver nanoparticles (AgNPs) were characterized by UV-visible spectra, X-ray diffraction (XRD) patterns, Energy Dispersive Analysis of X-rays (EDAX) and Fourier Transform Infrared (FTIR) analysis. The antifungal activity of the synthesized silver nanoparticles was evaluated against selected Candida species.
Results:
The synthesized AgNPs showed a surface plasmon resonance peak at 425 nm. XRD patterns showed the crystalline peaks at 38.15° (111), 44.35° (200), 64.52° (220) and 77.49° (311) matching with the diffraction facets of silver. The size of the AgNPs was in the range of 20-45 nm. The EDAX analysis revealed the presence of silver as the major metal in the sample. The synthesized AgNPs showed anticandidal activity against Candida albicans, Candida tropicalis and Candida krusei with a maximum zone of inhibition of 20mm against C. albicans.
Conclusions:
The results of this study suggest that the green synthesis of silver nanoparticles using Streptomyces sp.VITPK1 have the ability to act against pathogenic Candida strains.
Silver nanoparticles (NPs) have been the subjects of researchers because of their unique properties (e.g., size and shape depending optical, antimicrobial, and electrical properties). A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. This review presents an overview of silver nanoparticle preparation by physical, chemical, and biological synthesis. The aim of this review article is, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of the above mentioned techniques for industries.
A review is presented of the nutritional requirements and physiology of actinomycetes, with special emphasis on: (a) selective isolation of unusual forms; (b) colonial morphogenesis and induction of sporulation; (c) biosynthesis of secondary metabolites of value, with particular reference to antibiotics and industrial enzymes. The future potential of actinomycetes as major contributors of useful bioactive metabolites is also indicated.
The present study reports antioxidant activity of melanin pigment from actinomycete strain D5 isolated from Thar Desert soil, Rajasthan, India. Melanin production
by the strain D5 was confirmed using tyrosine agar. Melanin production was carriedout by adopting solid state fermentation using wheat bran and rice bran medium and
extracted using ethyl acetate. About 280 mg/10 gram and 192 mg of crude pigment were extracted from 10 gram of wheat bran and rice bran medium, respectively. The
melanin pigment from crude extract was partially purified by preparative TLC and the purified melanin fraction showed good free radical scavenging activity in DPPH
method. The actinomycete strain D5 was characterized and identified as Streptomyces girseorubiginosus (D5) based on their phenotypic characteristics. Further
fermentation and purification of melanin pigment from strain D5 will leads to a development of pharmaceutically valuable antioxidant
Marine actinobacteria are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Actinobacteria from terrestrial sources have been studied and screened since the 1950s, for many important antibiotics, anticancer, antitumor and immunosuppressive agents. However, frequent rediscovery of the same compounds from the terrestrial actinobacteria has made them less attractive for screening programs in the recent years. At the same time, actinobacteria isolated from the marine environment have currently received considerable attention due to the structural diversity and unique biological activities of their secondary metabolites. They are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, antitumor, cytotoxic, cytostatic, anti-inflammatory, anti-parasitic, anti-malaria, antiviral, antioxidant, anti-angiogenesis, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.
The science and technology of nanomaterials has created great excitement and expectations in the last few years. By its very nature, the subject is of immense academic interest, having to do with very tiny objects in the nanometer regime. There has already been much progress in the synthesis, assembly and fabrication of nanomaterials, and, equally importantly, in the potential applications of these materials in a wide variety of technologies. The next decade is likely to witness major strides in the preparation, characterization and exploitation of nanoparticles, nanotubes and other nanounits, and their assemblies. In addition, there will be progress in the discovery and commercialization of nanotechnologies and devices. These new technologies are bound to have an impact on the chemical, energy, electronics and space industries. They will also have applications in medicine and health care, drug and gene delivery being important areas. This article examines the important facets
of nanomaterials research, highlighting the current trends and future directions. Since synthesis, structure, properties and simulation are important ingredients of nanoscience, materials chemists have a major role to play.
SUMMARY The aerobic nocardioform actinomycete, found to be common in herbivore dung and aquatic habitats and previously given the trivial name Lspi, was studied along with representative strains of taxa within the 'rhodochrous ' complex. Lspi strains were recovered as a homogeneous cluster which separated from the other reference strains at the 69 % similarity level in a numerical taxonomic analysis. The specific name Rhodococcus coprophilus is proposed for this new species. We also consider the generic name Rhodococcus Zopf to be appropriate for most of the species currently accommodated within that rather ill-defined taxon known as the ' rhodochrous ' complex and variously classified within the genera Nocardia, Mycobacterium, Jensenia, Corynebacrerium or Gordona.
a b s t r a c t Biosynthesis has led to the development of various biomimetic approaches for the fabrication of nanoscale materials. The present study reveals a unique procedure for the biosynthesis of bactericidal silver nanoparticles (AgNPs) using a novel Streptomyces sp. BDUKAS10, an isolate of mangrove sediment. Aque-ous silver nitrate (AgNO 3) solution was treated with cell free supernatant (CFS) of the isolate to synthesize bactericidal silver nanoparticles. Initial characterization was performed by visual observation for color change to intense brown color. UV–visible spectrophotometry (UV–vis) for measuring surface plasmon resonance indicated a maximum absorption peak at 441 nm. Fourier Transform Infrared Spectroscopy (FTIR) analysis provides evidence for proteins as possible reducing, and capping agents. Energy disper-sive X-ray (EDAX) spectroscopy analysis showed elemental silver as major signal. Transmission Electron Microscopy (TEM) study indicated spherical silver nanoparticles in the size range of 21–48 nm. Com-pared to the CFS, the biosynthesized AgNPs exemplified superior bactericidal efficacy towards the tested bacterial strains. Results from this study suggested that Streptomyces sp. BDUKAS10 can be advanta-geous for the synthesis of AgNPs by extracellular method in the view of sustainable and ecofriendly approach.
Low-input agriculture is likely to be the focal point for future cropping systems. Worldwide there is increasing concern that we must decrease the use of chemicals in agriculture. A leading reason for this concern has been the effects of pesticides on food quality, consumer health, and the environment. There also is concern regarding fertilizers and energy inputs because of environmental pollution from excessive application rates and poor timing of fertilization and because of the depletion of nonrenewable energy resources. Overuse of these materials not only is an economic waste but also may require environmental cleanup. Legislation may mandate the development of alternative methods of pest control. For example, the Dutch Government has demanded a 35% decrease in the use of farm pesticides in 1995 and a 50% reduction by the year 2000. Other governments may impose similar limitations.
Extracellular biosynthesis of monodisperse gold nanoparticles was discussed. Actinomycete, a microorganism, was used to react with aqueous chloroaurate ions. Results showed that there is a reduction of the metal ions and stabilization of gold nanoparticles which is due to an enzymatic process.
S ummary
A mixture of bacteria and a vesicular‐arbuscular mycorrhizal fungus isolated from field‐collected sods of blue grama ( Bouteloua gracilis (H.B.K.) Griffiths) were tested for their interaction in the rhizosphere of pot‐grown blue grama plants. Populations of the inoculated bacterial species and actinomycete populations, as influenced by the presence or absence of Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe, were enumerated by dilution plate counts from rhizosphere and non‐rhizosphere soil samples. Total bacterial counts and the population of one bacterial species in the non‐rhizosphere soil of pots containing plants were significantly greater than in soil of pots without plants. The population of two bacterial species and actinomycetes were not significantly different in the non‐rhizosphere soil of both mycorrhizal and non‐mycorrhizal plant treatments when compared to the soil of pots without plants. In the rhizosphere of mycorrhizal plants, the total bacterial population and colony counts of one of the four bacterial isolates, when expressed as colony‐forming units (CFU) per gram of root dry weight, were significantly reduced compared with controls. The numbers of CFU per gram of rhizosphere soil of one bacterial species were significantly increased by the presence of the mycorrhizal fungus. Although no significant negative correlation was observed between populations of bacterial species in the rhizosphere soils, significant positive correlations between specific bacterial populations depended on whether or not the roots were mycorrhizal.
An isolation method for actinoplanetes is described which uses the ability of the sporangium to withstand desiccation and release motile spores when subsequently rehydrated. The desiccation stage reduces the number of associated Gram negative bacteria which cause problems when attempts are made to isolate species on agar plates from natural substrates. The method has enabled the isolation of actinoplanetes directly from soil and plant litter and indirectly from soil with the aid of baits such as pollen and hair. Actinoplanetes appear to be common in dry soils collected from arid areas and sand dune systems. They are normally present on leaves submerged for a time in rivers, streams and lakes and subsequently deposited in heaps on shores or as debris on overhanging vegetation. An actinomycete resembling the ‘spore-dome’ organism recovered from leaves and twigs by Willoughby (1969) was frequently isolated during the course of these studies. Preliminary work suggests that different species can be recognized and could constitute a new genus within the family Streptomycetaceae.
A large number of mycolate actinomycetes have been recovered from deep-sea sediments in the NW Pacific Ocean using selective isolation methods. The isolates were putatively assigned to the genus Rhodococcus on the basis of colony characteristics and mycolic acid profiles. The diversity among these isolates and their relationship to type strains of Rhodococcus and other mycolate taxa were assessed by Curie point pyrolysis mass spectrometry (PyMS). Three major (A, C, D) and two minor (B, E) groups were defined by PyMS. Cluster A was a large group of isolates recovered from sediment in the Izu Bonin Trench (2679 m); Cluster C comprised isolates from both the Izu Bonin Trench (6390 and 6499 m) and from the Japan Trench (4418, 6048 and 6455 m). These Cluster C isolates showed close similarity to Dietzia maris and this was subsequently confirmed using molecular methods. Cluster D contained isolates recovered from a sediment taken from a depth of 1168m in Sagami Bay and were identified as members of the terrestrial species Rhodococcus luteus. Clusters B and E had close affinities with members of the genera Gordonia and Mycobacterium. The presence of Thermoactinomyces in certain of the deep-sea sediments studied was indicative of the movement of terrestrial material into the ocean depths.
16S ribosomal RNA gene sequence analyses produced excellent definition of most genera of the mycolata, and indicated that the among the deep sea isolates (1) were novel species of Corynebacterium, Gordonia and Mycobacterium, and (2) a Sea of Japan isolate the phylogenetic depth of which suggests the possibility of a new genus. Polyphasic taxonomic analysis revealed considerable diversity among the deep sea rhodococci and evidence for recently diverged species or DNA groups.
The effectiveness of twoStreptomyces spp. strains to controlpathogenic fungi was studied in stored maizegrain. The treatments included seeddisinfection and inoculation withStreptomyces spp. strains previously isolatedfrom maize rhizosphere. Actinomycete inoculumconsisted of filtered suspension and totalsuspension of fermentor-producedStreptomyces spp. strains biomass. Treatmentswith Streptomyces spp. strains aloneeffectively suppressed the development ofAspergillus spp., Curvularia lunata, andDrechslera maydis and significantly(p < 0,05) reduced the incidence ofFusarium subglutinans and Cephalosporiumacremonium. Among the inoculation treatments,nondisinfested seed inoculated with filteredsuspension was the only treatment that did notsuppress the development of Penicilliumspp. Maize seed inoculation with totalsuspension of strains was the most effectivetreatment to control the incidence of seedpathogenic fungi. The development of theDiplodia maydis was only suppressed by thecombination of seed disinfection andinoculation with total suspension of strains.Although, the strain DAUFPE 11470 showed thegreatest effectiveness for controlling thefungi pathogenic to seed, root and shootdevelopment was reduced by treatment with thisstrain.The results indicate thatStreptomyces spp. strains reduce the incidenceof seed pathogenic fungi and have potential asa biological control agent. However, an efficient methodof seed treatment with the biological controlagent must be developed before it can become anagricultural practice.