Rice (Oryza sativa L.) straw, an agricultural waste of high yield, is a sustainable source of fermentable sugars for biofuel and other chemicals. However, it shows recalcitrance to microbial catalysed depolymerization. We herein describe development of thermotolerant microbial consortium (RSV) from vermicompost with ability to degrade rice straw and analysis of its metagenome for bacterial diversity, and lignocellulolytic carbohydrate active enzymes (CAZymes) and their phylogenetic affiliations. RSV secretome exhibited cellulases and hemicellulases with higher activity at 60 °C. It catalysed depolymerization of chemical pretreated rice straw as revealed by scanning electron microscopy and saccharification yield of 460 mg g−1 rice straw. Microbial diversity of RSV was distinct from other compost habitats, with predominance of members of phyla Firmicutes, Proteobacteria and Bacteroidetes; and Pseudoclostridium, Thermoanaerobacterium, Chelatococcus and Algoriphagus being most abundant genera. RSV harboured 1389 CAZyme encoding ORFs of glycoside hydrolase, carbohydrate esterase, glycosyl transferase, carbohydrate binding module and auxiliary activity functions. Microorganisms of Firmicutes showed central role in lignocellulose deconstruction with importance in hemicellulose degradation; whereas representatives of Proteobacteria and Bacteroidetes contributed to cellulose and lignin degradation, respectively. RSV consortium could be a resource for mining thermotolerant cellulolytic bacteria or enzymes and studying their synergism in deconstruction of chemically pretreated rice straw.

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Carbon‐13 NMR signal assignments of the labdane diterpenoids andrographolide and 14‐deoxyandrographolide, along with their acetates, and isodeoxyandrographolide have been made. This study indicates that the C‐6 and C‐11 resonance assignments of isovirescenol‐B, made earlier, should be interchanged.

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Thermoactive xylanases have important applications in the industrial deconstruction of lignocellulosic plant biomass, due to their sustained activity even at high temperature conditions of industrial bioreactors. We herein report the development of a thermoactive xylanolytic microbial consortium from the semi-digested contents of goat rumen and characterization of the xylanolytic enzyme cocktail produced by it. The consortium exhibited maximum endoxylanase activity at pH6 and at 60°C. Zymogram analysis revealed the production of multiple xylanases. The xylanase cocktail was stable over a pH range of 5–9 after pre-incubation for 3 h. It retained 74% activity after pre-incubation (60°C) for 50 min. It’s activity was enhanced in presence of β-mercaptoethanol, NH4+, Mg2⁺ and Ca2⁺, whereas Hg2⁺ had an inhibitory effect. The xylanolytic cocktail was further utilized for the saccharification of alkali pre-treated rice straw and mushroom spent rice straw. Saccharification was studied quantitatively using the dinitrosalicylic acid method and qualitatively using scanning electron microscopy. Results indicated the potential of the xylanolytic cocktail for the saccharification of rice straw and highlighted the significance of chemical and/or biological pre-treatment in improving the accessibility of the substrate towards the xylanase cocktail.

In the course of our investigation in finding the potentialities of various microorganisms in transforming organic compounds, particularly steroidal hormones, Gibberella fujikuroi has been used. Literature survey (1-4) revealed that not much work has so far been done on the transformation of steroids by this particular fungus. Transformation of some flavonoids have been reported by UDUPA et al. (5,6). This prompted us to use this fungus in bringing about transformations of both steroids and aromatic compounds. For the present investigation testosterone (Ia) was used as the substrate.The strain of G. fujikuroi NCIM 665 used for the present work was kindly supplied by the National Collection of Industrial Microorganisms, Division of Biochemistry, National Chemical Laboratory, Poona, India. Preparation of slant cultures for inoculum and fermentation procedure were essentially those of UDUPA et al. (6). The only modification made by us was that the fermentation was carried out in a shaker instead of by intermittent aeration. The fermentation was carried out in 500-ml conical flasks (20 such flasks were used) each containing 100 ml of modified Czapek-Dox medium (7, 8) adjusted to pH 6.2. The flasks were sterilized at 15 P.S.I. for 15 min and inoculated with 6-day-old culture of G. fujikuroi grown on the slant culture of same compositions with agar (15 g/l). To each of the flasks, 10 mg (0.035 mM) of testosterone (in 1 ml acetone) was then added under sterile condition and the flasks were agitated in a rotary shaker (180 rpm) at 28°+ 1° for 20 days. The whole broth was then acidified with HCl (1: 1) and extracted with chloroform. This extract was found to contain two major steroidal compounds in addition to unreacted testosterone (in a very small amount) and other minor steroidal compounds (all Liebermann positive) as compared to the control. TLC was carried out on silica gel (Gouri Chemical Works, Calcutta), with a solvent system of benzene: chloroform: methanol 339

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