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Activity and stability of invertase obtained from Saccharomyces cerevisiae MTCC 170 were characterized with parameters like pH, temperature, metal ions, surfactants and chemical inhibitors. The pH stability of this enzyme was observed between pH 2 and 9 with an average of 63% retaining activity for 24 h. The crude enzyme showed optimum activity at pH 6 and 30°C. Enzyme activity was increased in the presence of 5 mM CaCl 2 (89.11%). Maximum invertase activity of 32.32% was recorded at polyethylene glycol (1%). Maximum invertase activity of 25.58% was recorded at EDTA for S. cerevisiae MTCC 170. The kinetic parameters (Km and Vmax) were determined at 30°C and pH 6 for S. cerevisiae MTCC 170 invertase for concentrations ranging from 0.5 to 5 mg/ml of sucrose as substrate. The Km and Vmax of S. cerevisiae MTCC 170 are 0.6894 mg/ml and 0.3201 μm/min/mg.

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Keratinase producing bacterium Bacillus megaterium RS1 was obtained from feather dumping site of Rajapalayam. The optimal level of the key variables (starch, feather meal, calcium chloride) was used to determine the effect of their interactions on keratinase production using the statistical tool [(Central composite design (CCD) of response surface methodology (RSM)]. The second-order quadratic model with the optimum conditions [(starch (1%); feather meal (3%) and calcium chloride (0.02%)] was used. The nearness of the coefficient of determination (R 2 = 1.0000) to 1 ensures the satisfactory adjustment of the quadratic model to the experimental data. The maximum keratinase production was 142.9 U/ml.