Browsing by Author "Vijay Chandra Verma"

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Host-mimetic metabolomics of endophytes: Looking back into the future
(Springer India, 2014) Vijay Chandra Verma; Satya Prakash; Rana Gopal Singh; Alan Christopher Gange
Endophytic research is now gaining pace together with the technological advancement and refinements. The phenomenal potential of endophytes as prolific producer of a wide range of bioactive compounds occupies a complimentary domain of natural product research. The discovery of paclitaxel (Taxol) as bioactive natural product of endophytic origin seems to draw indisputable attention not only for their antitumor activity but as potential microbial alternative for this high in-demand drug. Plenty of opinion is given by the enthusiasts on microbial production of paclitaxel as phylogenetic process and driving paradigm of evolution; however, skeptics described it as phylogenetic anomalies. But despite being highly controversial, the horizontal gene transfer (HGT) theory still seems quite justifiable. Let's have another example: maytansinoid, a potent cytotoxic agent, was isolated and characterized from microbial endophyte of the same plant; however in both cases, further investigations recorded their occurrence not only in same host but also from deferent distant hosts and even from different endophytes. So the report of taxane and related taxoids from a taxonomically distant host raises several questions. One may assume that this might be due to evolutionary invention; however, it is very unlikely to accept that all modules of gene responsible for biosynthesis of these molecules invented in microbial systems during long evolutionary symbiosis. With this chapter we are trying to get into the mechanistic aspects of host-specific chemicals synthesized by endophytic microbes together with our experience with isolation and characterization of host-specific compounds like piperine and azadirachtin. Nevertheless, the significance of this potential of endophytes cannot be ignored, as it provides not only alternative source to existing pharmaceuticals but also on the other hand save the valuable biodiversity of highly medicinal plants. © 2014 Springer India. All rights reserved.
Myconanosynthesis: Redefining the role of microbial endophytes
(Springer India, 2014) Santosh Kumar Singh; Amit Ranjan; Shriti Singh; Swechha Anand; Vijay Chandra Verma
In recent years, a surge of interest was observed in synthesizing nanoparticles and other highly structured nanomaterials using microbes. Plenty of reports in cited domain claims synthesis of nanomaterials with desired shape, size and architecture through fungi, bacteria and actinomycetes. More precisely, fungi are frequently reported for their pivotal potential in bioreduction of the aqueous metal ions into their respective nanomaterials. The sporadic reports of nanomaterial synthesis from fungi led to the development of 'myconanotechnology' as a new domain of nanotechnology. This newly emerging domain of nanotechnology attracts not only the microbiologist but also material chemists and technologists, because of safe, sustainable and non-toxic 'green chemistry' associated with it. There is possibility of getting a total control over shape and size in a microbial system more easily than chemical methods. So far, a number of fungal strains have been reported for this potential among which some most common are Aspergillus, Fusarium, Colletotrichum, Penicillium, Verticillium, etc. However, the exact mechanism of this mycoreduction is not known so far, but it is speculated that fungal enzymes and/or metabolites are usually responsible for reduction of metal ions into their respective nanoparticles. Although many soil and pathogenic fungi have been reported as nano-factories of desired metals, relatively few reports are available about the synthesis of nanomaterials using fungal endophytes. It's surprising since fungal endophytes occupying the unusual habitat have potential to survive under stress conditions and thus must have set of enzymes and metabolites not found in their wild-type counterparts. For this reason, fungal endophytes could be a better candidate for synthesizing nanomaterials. We, in this review, provide a brief review of recent account about endophyte-mediated synthesis of nanomaterials. © 2014 Springer India. All rights reserved.