Search

Hot springs are geothermally heated underground water that create a natural habitat for diverse thermophilic microorganisms. The study presents a comprehensive investigation of microbial diversity and functional potential of four thermal water reservoirs of 55 to 98 °C temperature range, located in Tattapani geothermal field of Chhattisgarh, India, by using culture-independent metagenome sequencing approach. The MG-RAST taxonomic profiling of metagenome samples revealed the predominance of bacterial domains (94.8 to 98.2%), followed by archaea (1.1 to 4.8%), eukaryota (0.1 to 0.5%), and viruses (0.04 to 0.09%). The quality filtered reads (42.1 to 68.1 million) were assembled into 66 to 330 thousand non-redundant contigs (>200 bp length) in the four metagenome samples. The functional annotation using CAZy database identified a total of 4083 putative genes with functional domains involved in catalysis of carbohydrate degradation or modification or synthesis of glycosidic bonds. The study detected many novel biocatalysts associated with hydrolysis of lignocellulosic biomass polymers- cellulose, hemicellulose, lignin, and pectin. Metagenome assembly and catalytic functions of two metagenomic contigs, encoding β-glucosidase, and xylanase, were experimentally validated. The findings emphasized these geothermal water reservoir sites as the repository of biocatalyst-encoding genes of carbohydrate-related and lignocellulosic biomass processing significance., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Withania somnifera is one of the most important medicinal plants of Ayurveda and finds extensive uses in Indian traditional herbal preparations. In this investigation, selected accessions of the plant were examined for diversity through RAPDs, isoenzymes, polypeptide polymorphism and withanolide profiles. The accessions clustered together with respect to their characteristic profile of major withanolides and represented withaferin A, withanone, withanolide D or withanolide A rich groups. This level of phytochemical diversity as discrete chemotypes is widest and is being first ever documented to occur in Indian population of the plant.

2-Mercaptoethanol reacts selectively with the 5beta,6beta-epoxy steroids isolated from Withania somnifera substituting the epoxide by a six-membered oxyethylene-2'-thio ring whereas it failed to show such reactivity on 6alpha,7alpha-epoxy withasteroids. The structure of the product has been elucidated by spectroscopic methods, especially applying extensive 2D NMR methods. The anticancer activity of withaferin A was lost in the reaction product indicating that its activity is also linked to the free 5beta,6beta-epoxide functional group.

Two new and seven known withanolides along with beta-sitosterol, stigmasterol, beta-sitosterol glucoside, stigmasterol glucoside, alpha+beta glucose were isolated from the roots of Withania somnifera. Among the known compounds, Viscosa lactone B, stigmasterol, stigmasterol glucoside and alpha+beta glucose are being reported from the roots of W. somnifera for the first time. One of the new compounds contained the rare 16beta-acetoxy-17(20)-ene the other contained unusual 6alpha-hydroxy-5,7alpha-epoxy functional groups in the withasteroid skeleton. The structures were elucidated by spectroscopic methods and chemical transformations.

Four (1, 8-10) and six known (2-7) withanolides were isolated from the leaves of Withania somnifera. Among the new compounds, 10 possessed the rare 3-O-sulfate group with the saturation in A ring and 9 contained unusual 1,4-dien-3-one group. Compound 8 did not have usual 2,3 unsaturation in A ring while 1 had the rare C-16 double bond. The structures of all the compounds were elucidated by spectroscopic methods and chemical transformation.