Sharma, NiveditaGitanjali2017-06-032017-06-032015http://krishikosh.egranth.ac.in/handle/1/5810017010Mushroom compost being a highly probable source for amylogenic microorganisms was utilized as a source for isolation of amylolytic microorganisms. In total, 13 amylolytic bacteria have been screened from mushroom compost. Among them, alkalothermophilic hyperamylogenic strains GC6 and GV2 were selected and identified as B. aerius GC6 |KJ 775810.1| and B. sonorensis GV2 |KJ775811.1|. Cultural conditions and process parameters viz. media types, pH, temperature, inoculum size, incubation time, substrate concentration, divalent ions and surfactants etc. were optimized firstly through classical one variable at a time (OVAT) followed by statistical optimization by employing central composite design of response surface methodology. The enzymes obtained from both the strains were purified to homogeneity by following a sequential purification approach. B. aerius GC6 α-amylase was purified to a final purification fold of 17.86 and had a molecular weight of 43 kDa whereas B. sonorensis GV2 α-amylase was purified to a final purification fold of 14.52 and had a molecular weight of 45 kDa. α-amylase activity was found to be maximum at 50 oC and pH 9.0 for B. aerius GC6 and at 50 oC and pH 10.0 for B. sonorensis GV2. α-amylase from both the strains was quite thermostable with retention of more than 50% activity after incubation of 90 min at 45-60 oC. Kinetic characteristics of α-amylase from both the strains showed that the enzyme was very efficient qualitatively as well as quantitatively. Raw starch adsorption and hydrolysis ability shown by α-amylase from both the strains is a rare feature of bacterial α-amylase making it a potential candidate for starch processing industry. Immobilization of purified α-amylase from both the strains onto natural hydrogels showed a considerable retention upto 8 cycles however immobilization using iron oxide nano particles proved to be quite stable with apparently no loss in activity even after 20 cycles. Applicability of purified α-amylase from B. aerius GC6 was assessed by utilizing it for the hydrolysis of Hydrodictyon biomass for the production of bioethanol. Mixture of α-amylase, β-amylase, cellulase and pectinase from potential inhouse microorganisms was used for saccharification of biomass followed by its fermentation to ethanol using S. cerevisiae-I (MTCC3089). A final ethanol concentration of 13.93 g/l and 16.67 g/l with a fermentation efficiency of 64.84% and 66.68% was obtained in a stirred tank bioreactor under separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) mode respectively. This is the first report on α- amylase from B. aerius and B. sonorensis. Thermal and alkaline stability of this enzyme makes them a potential candidate for use in starch processing industry.enenzymes, productivity, fermentation, starch, bacteria, concentrates, proteins, biomass, alcohols, polysaccharidesThesis