Browsing by Author "Vijay C. Verma"

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Advances in endophytic research
(Springer India, 2014) Vijay C. Verma; Alan C. Gange
In recent years there has been significant attention paid on the endophytic research by various groups working within this domain. Mutualistic endophytic microbes with an emphasis on the relatively understudied fungal endophytes are the focus of this special book. Plants are associated with micro-organisms: endophytic bacteria and fungi, which live inter- and intra-cellularly without inducing pathogenic symptoms, but have active biochemical and genetic interactions with their host. Endophytes play vital roles as plant growth promoters, biocontrol agents, biosurfactant producers, enzymes and secondary metabolite producers, as well as providing a new hidden repertoire of bioactive natural products with uses in pharmaceutical, agrochemical and other biotechnological applications. The increasing interest in endophytic research generates significant progress in our understanding of the host-endophyte relationship at molecular and genetic level. The bio-prospection of microbial endophytes has led to exciting possibilities for their biotechnological application as biocontrol agent, bioactive metabolites, and other useful traits. Apart from these virtues, the microbial endophytes may be adapted to the complex metabolism of many desired molecules that can be of significant industrial applications. These microbes can be a useful alternative for sustainable solutions for ecological control of pests and diseases, and can reduce the burden of excess of chemical fertilizers for this purpose. This book is an attempt to review the recent development in the understanding of microbial endophytes and their potential biotechnological applications. This is a collection of literature authored by noted researchers having signatory status in endophytic research and summarizes the development achieved so far, and future prospects for further research in this fascinating area of research. © 2014 Springer India. All rights reserved.
An endophytic fungus from Azadirachta indica A. Juss. that produces azadirachtin
(2012) Souvik Kusari; Vijay C. Verma; Marc Lamshoeft; Michael Spiteller
Azadirachtin A and its structural analogues are a well-known class of natural insecticides having antifeedant and insect growth-regulating properties. These compounds are exclusive to the neem tree, Azadirachta indica A. Juss, from where they are currently sourced. Here we report for the first time, the isolation and characterization of a novel endophytic fungus from A. indica, which produces azadirachtin A and B in rich mycological medium (Sabouraud dextrose broth), under shake-flask fermentation conditions. The fungus was identified as Eupenicillium parvum by ITS analysis (ITS1 and ITS2 regions and the intervening 5. 8S rDNA region). Azadirachtin A and B were identified and quantified by LC-HRMS and LC-HRMS2, and by comparison with the authentic reference standards. The biosynthesis of azadirachtin A and B by the cultured endophyte, which is also produced by the host neem plant, provides an exciting platform for further scientific exploration within both the ecological and biochemical contexts. © 2011 Springer Science+Business Media B.V.
Anticestodal activity of endophytic Pestalotiopsis sp. on protoscoleces of hydatid cyst echinococcus granulosus
(2013) Vijay C. Verma; Mayank Gangwar; Madhu Yashpal; Gopal Nath
Surgery is still the main treatment in hydatidosis caused by Echinococcus, which is a global health problem in human and animals. So, there is need for some natural protoscolicidal agents for instillation to prevent their reoccurrence at therapeutic doses. In this present investigation, anticestodal activity of one of the endophytic fungi Pestalotiopsis sp. from Neem plant was observed on protoscoleces of hydatid cysts of Echinococcus granulosus. Viability of protoscoleces was confirmed by 0.1% aqueous eosin red stain method, where mortality was observed at different concentrations with respect to time. An average anticestodal activity was observed with different endophytic fungal strains, that is, Nigrospora (479 ± 2.9), Colletotrichum (469 ± 25.8), Fusarium (355 ± 14.5), and Chaetomium (332 ± 28.3) showing 64 to 70% protoscolicidal activity, except Pestalotiopsis sp. (581 ± 15.0), which showed promising scolicidal activity up to 97% mortality just within 30 min of incubation. These species showed significant reduction in viability of protoscoleces. This is the first report on the scolicidal activity of endophytic Pestalotiopsis sp. We conclude that ultrastructural changes in protoscoleces were due to endophytic extract suggesting that there may be some bioactive compounds that have selective action on the tegument layer of protoscoleces. As compared with that of standard drug used, endophytic species of Neem plant shows significant anticestodal activity. © 2013 Vijay C. Verma et al.
Biofabrication of Anisotropic Gold Nanotriangles Using Extract of Endophytic Aspergillus clavatus as a Dual Functional Reductant and Stabilizer
(Springer New York LLC, 2011) Vijay C. Verma; Santosh K. Singh; Ravindra Solanki; Satya Prakash
Biosynthesis of metal and semiconductor nanoparticles using microorganisms has emerged as a more eco-friendly, simpler and reproducible alternative to the chemical synthesis, allowing the generation of rare forms such as nanotriangles and prisms. Here, we report the endophytic fungus Aspergillus clavatus, isolated from surface sterilized stem tissues of Azadirachta indica A. Juss., when incubated with an aqueous solution of chloroaurate ions produces a diverse mixture of intracellular gold nanoparticles (AuNPs), especially nanotriangles (GNT) in the size range from 20 to 35 nm. These structures (GNT) are of special interest since they possess distinct plasmonic features in the visible and IR regions, which equipped them with unique physical and optical properties exploitable in vital applications such as optics, electronics, catalysis and biomedicine. The reaction process was simple and convenient to handle and was monitored using ultraviolet-visible spectroscopy (UV-vis). The morphology and crystalline nature of the GNTs were determined from transmission electron microscopy (TEM), atomic force spectroscopy (AFM) and X-ray diffraction (XRD) spectroscopy. This proposed mechanistic principal might serve as a set of design rule for the synthesis of anisotropic nanostructures with desired architecture and can be amenable for the large scale commercial production and technical applications. © 2010 The Author(s).
Biosynthesis of antimicrobial silver nanoparticles by the endophytic fungus Aspergillus clavatus
(2010) Vijay C. Verma; Ravindra N. Kharwar; Alan C. Gange
Aim: To induce the biosynthesis of silver nanoparticles (AgNPs) using Aspergillus clavatus and evaluate their antimicrobial potential. Materials & methods: Aspergillus clavatus (AzS-275), an endophytic fungus isolated from sterilized stem tissues of Azadirachta indica A. Juss., was challenged with 1 mM AgNO3 solution. The characterization of the AgNPs was carried out by x-ray diffraction spectrometry, transmission-electron microscopy and atomic force microscopy. Results & discussion: The synthesized AgNPs were found to be extracellular, polydispersed spherical or hexagonal particles ranging from 10 to 25 nm in size. Antimicrobial activity was performed using a disc-diffusion method against Candida albicans, Pseudomonas fluorescens and Escherichia coli. The results showed an average minimum inhibitory concentration of 5.83μg ml-1 and minimum fungicidal concentration of 9.7 μg ml -1 against C. albicans. Conclusions: AgNPs can be mycosynthesized extracellularly using A. clavatus as the fungal system, which is highly advantageous over chemical synthesis not only because it can be synthesized on a large scale, but because of the ease of downstream processing and its biomedical application in antimicrobial activity. © 2010 Future Medicine Ltd.
Chemical and functional diversity of natural products from plant associated endophytic fungi
(Natural Product Incorporation, 2009) Vijay C. Verma; Ravindra N. Kharwar; Gary A. Strobel
This review describes examples of naturally occurring bioactive compounds obtained from fungal endophytes from various host plants. The main topics addressed are sources, identification, biological activity, biosynthesis, and ecological and chemosystematic significance of those bioactive compounds whose sources were well defined.
Correction to Biofabrication of anisotropic gold nanotriangles using extract of endophytic Aspergillus clavatus as a dual functional reductant and stabilizer (Nanoscale Research Letters, (2011), 6, (261))
(2011) Vijay C. Verma; Ravindra N. Kharwar; Santosh K. Singh; Ravindra Solanki; Satya Prakash
[No abstract available]
Endophytic actinomycetes from azadirachta indica A. Juss.: Isolation, diversity, and anti-microbial activity
(2009) Vijay C. Verma; Surendra K. Gond; Anuj Kumar; Ashish Mishra; Ravindra N. Kharwar; Alan C. Gange
Endophytic actinomycetes from Azadirachta indica A. Juss. were screened and evaluated for their anti-microbial activity against an array of pathogenic fungi and bacteria. A total of 55 separate isolates were obtained from 20 plants, and 60% of these showed inhibitory activity against one or more pathogenic fungi and bacteria. Actinomycetes were most commonly recovered from roots (54.5% of all isolates), followed by stems (23.6%), and leaves (21.8%). The dominant genus was Streptomyces (49.09% of all isolates), while Streptosporangium (14.5%), Microbispora (10.9%), Streptoverticillium (5.5%), Sacchromonospora sp. (5.5%), and Nocardia (3.6%) were also recovered. Streptomyces isolates AzR 006, 011, and 031 (all from roots) had acute activity against Pseudomonas fluorescens, while AzR027, 032, and 051 (also all from roots) showed activity against Escherichia coli. Meanwhile, an isolate of Nocardia sp. from leaves (AzL025) showed antagonism against Bacillus subtilis. Overall, 32 of the 55 were found to have broad spectrum significant antimicrobial activity, while about 4% of them showed strong and acute inhibition to pathogenic fungi and bacteria. Isolates of Streptomyces AzR031, 008, and 047, Nocardia sp. AzL025, and Streptosporangium sp. AzR 021 and 048 are of particular interest because they showed significant antagonistic activity against root pathogens, including Pythium and Phytophthora sp. Thus, many of the isolates recovered from A. indica in this study may be used in developing potential bio-control agents against a range of pathogenic fungi and bacteria and in the production of novel natural antimicrobial compounds. These results not only further our understanding of plant-microbe interactions but also indicate that there is an untapped resource of endophytic microorganisms that could be exploited in the biotechnological, medicinal, and agricultural industries. © 2008 Springer Science+Business Media, LLC.
Endophytic Fungal Flora from Roots and Fruits of an Indian Neem Plant Azadirachta indica A. Juss., and Impact of Culture Media on their Isolation
(2011) Vijay C. Verma; Surendra K. Gond; Anuj Kumar; Ravindra N. Kharwar; Lori-Ann Boulanger; Gary A. Strobel
Azadirachta indica A. Juss. (neem), native to India, is well known worldwide for its insecticidal and ethanopharmacological properties. Although endophytic microbes are known from this plant as only leaves and stems were the subjects of past reports. Now, a variety of procedures and a number of different media were used to isolate the maximum number of endophytic fungi from unripe fruits and roots. A total of 272 isolates of 29 filamentous fungal taxa were isolated at rate of 68.0% from 400 samples of three different individual trees (at locations-Az1, Az2, Az3). Mycological agar (MCA) medium yielded the highest number of isolates (95, with a 14.50% isolation rate) with the greatest species richness. Mycelia Sterilia (1, 2, 3) accounted for 11.06%, Coelomycetes 7.25%, while Hyphomycetes showed the maximum number of representative isolates (81. 69%). Mycelia-Sterilia (1, 2, 3), based on their 5. 8S ITS 1, ITS2 and partial 18S and 28S rDNA sequences were identified as Fusarium solani (99%), Chaetomium globosum (93%) and Chaetomium globosum (93%) respectively. Humicola, Drechslera, Colletotrichum, and Scytalidium sp. were some of the peculiar fungal endophytes recovered from this plant. © 2011 Association of Microbiologists of India.
Engineered Nanomaterials for Purification and Desalination of Palatable Water
(Wiley Blackwell, 2015) Vijay C. Verma; Swechha Anand; Mayank Gangwar; Santosh K. Singh
Despite more than two-thirds of the earth's surface being covered by water, people are facing inadequate access to potable water and are thus forced to use contaminated water from unhygienic sources. A major consequence of using contaminated water for preparing food or other daily uses is acute and chronic illness that is widespread especially in third-world countries. Apart from this, the scarcity of safe drinking water in many parts of the world and the increasing divide between availability and per capita utilization is creating a global problem. Since approximately 97% of water on the earth is saline, recycled water through desalination can help to cope with this problem. In this chapter, we look at the state-of-the art technologies driven with modern nanotechnology for water purification and desalination. The rapid development of nanoscience has enabled the implementation of promising processes for providing improved palatability and hygiene of drinking water. Recent technologies like ultra- and nanofiltration as well as reverse osmosis (RO) create new enthusiasm in the fields of water desalination and purification. Nanomaterials and nanotechnology-based solutions are now an integral part of the research to overcome the ever-growing problems in all aspects of science, and since many traditional approaches of water purification are based on molecule-level separation, it is reasonable to expect novel nano-engineered water treatment approaches. There are several new concepts for the desalination of nonpalatable water using engineered membranes/nanoparticles. Aquaporin nanocomposites, the combination of carbon nanotubes (CNTs) with other metal oxides, and noble metal nanoparticles are some good examples in this field. Despite all these developments, there are still some limitations regarding scalability at an industrial scale. In this chapter, we analyze the recent developments in nanotechnology-based solutions for the purification of water to ensure safe drinking water for all. © 2014 John Wiley & Sons, Inc.
Javanicin, an antibacterial naphthaquinone from an endophytic fungus of neem, chloridium sp.
(2009) Ravindra N. Kharwar; Vijay C. Verma; Anuj Kumar; Surendra K. Gond; James K. Harper; Wilford M. Hess; Emil Lobkovosky; Cong Ma; Yuhao Ren; Gary A. Strobel
The endophytic fungus Chloridium sp. produces javanicin under liquid and solid media culture conditions. This highly functionalized naphthaquinone exhibits strong antibacterial activity against Pseudomonas spp., representing pathogens to both humans and plants. The compound was crystallized and the structure was elucidated by X-ray crystallography. The X-ray structure confirms the previously elucidated structure of the compound that was done under standard spectroscopic methods. The importance of javanicin in establishing symbiosis between Chloridium sp. and its host plant, Azadirachta indica, is briefly discussed. © 2008 Springer Science+Business Media, LLC.
Osmoregulatory and tegumental ultrastructural damages to protoscoleces of hydatid cysts Echinococcus granulosus induced by fungal endophytes
(Springer, 2014) Vijay C. Verma; Mayank Gangwar; Gopal Nath
Characteristic ultrastructural changes were observed when protoscoleces of hydatid cysts Echinococcus granulosus was treated with extract of endophytic fungi Eupenicillium and Chaetomium sp. isolated from Azadirachta indica and Piper longum plants respectively. A sharp decrease in viability of protoscoleces was observed after 6 h of incubation with fungal extracts. The ultrastructural changes included rosteller disorganization, loss of hooks and shedding of the microtriches of scolex region. The formation of digitiform projections on tegument layer which, increased in size as prolong incubation with extract and get burst, leading to a osmoregulatory damage into tegumental layers of parasite. This osmoregulatory damages caused the loss of turgidity due to leakage of cell contents, which might be the major cause of the mortality in treated parasites. It is remarkable, since very similar type of ultrastructural changes were observed with some pyrazinoisoquinoline derivatives, as praziquantel. Our initial results indicate that extract of endophytic Eupenicillium and Chaetomium spp. are having significant anti-cestodal activity and have selective activity on tegument layer. Further chemical prospection is required through rigorous bioassay guided fractionation coupled with robust high resolution mass spectrometric analysis to get final stereo-structures responsible for the parasiticidal activity. This initial strain selection outcome will serve a platform for isolation and characterization of new drug lead that can be useful in tailoring novel, safe and effective anthelmintics. © 2013, Indian Society for Parasitology.
Piperine production by endophytic fungus Periconia sp. Isolated from Piper longum L.
(2011) Vijay C. Verma; Emil Lobkovsky; Alan C. Gange; Santosh K. Singh; Satya Prakash
The endophytic fungus Periconia sp. produces piperine (5-(3, 4-methylenedioxyphenyl)-1-piperidinopent-2, 4-dien-1-one) under liquid culture. This is the first report of the alternative source for this chemical other than its host, Piper longum. The highly functionalized fungus-derived piperine exhibits strong antimycobacterial activity against Mycobacterium tuberculosis and M. smegmetis with minimum inhibitory concentrations of 1.74 and 2.62 μg ml-1, respectively. The compound was crystallized and the structure was elucidated by single-crystal X-ray crystallography. This finding is of significance as piperine is a potential cancer preventative agent. It is reaffirmed by this report that important pharmaceuticals can be produced by endophytic microbes, and these molecules appear to be mimetic to their host origin. Therefore, we can enhance the bioactive principles of medicinal plants by isolating and identifying the endophytes, thereby showing the importance of preserving the biodiversity of these plants. © 2011 Japan Antibiotics Research Association All rights reserved.
The endophytic fungal complex of Catharanthus roseus (L.) G. Don
(2008) Ravindra N. Kharwar; Vijay C. Verma; Gary Strobel; David Ezra
Catharanthus roseus (L.) is well known for its production of several anticancerous vinca alkaloids such as vincristine, vindesine, vinorelbine, vinblastin, and the recently discovered vinflunine. This plant is a host to a plethora of endophytic fungi. A total 183 endophytic fungi representing 13 fungal taxa were isolated from leaf, stem and root tissues of C. roseus from two sites representing two different ecosystems in North India. Interestingly, with two exceptions (one coelomycete and one ascomycete), all of the isolates were Hyphomycetes. Root tissues were heavily colonized by genera such as Alternaria, Cladosporium and Aspergillus. However, leaf tissues showed a greater diversity of endophytes and Drechslera, Curvularia, Bipolaris, Alternaria and Aspergillus spp. were the dominant fungi isolated. Interestingly, a fungus producing no fruiting structures was the most prevalent, isolated from C. roseus. On the basis of its partial ITS-5.8 S rDNA sequences, it was identified as Chaetomium globossum, with 99% sequence similarity (537/540). The species richness as well as frequency of colonization of endophytic fungi were pronounced in the root tissues at both sites (Loc 1, 38.6%; Loc 2, 33.7%). This study suggests that endophytes are both host- and tissue-specific. It also confirms that despite ecological variations, there were little differences in the species richness of fungal endophytes recovered from plants in the two different ecological sites.