Cow dung is an ideal fermentation medium for amylase production in solid-state fermentation by Bacillus cereus

摘要

Amylase production by Bacillus cereus IND4 was investigated by solid state fermentation (SSF) using cow dung substrate. The SSF conditions were optimized by using one-variable-at-a-time approach and two level full factorial design. Two level full factorial design demonstrated that moisture, pH, fructose, yeast extract and ammonium sulphate have significantly influenced enzyme production (p<0.05). A central composite design was employed to investigate the optimum concentration of these variables affecting amylase production. Maximal amylase production of 464units/ml of enzyme was observed in the presence of 100% moisture, 0.1% fructose and 0.01% ammonium sulphate. The enzyme production increased three fold compared to the original medium. The optimum pH and temperature for the activity of amylase were found to be 8.0 and 50^oC, respectively. This enzyme was highly stable at wide pH range (7.0-9.0) and showed 32% enzyme activity after initial denaturation at 50^oC for 1h. This is the first detailed report on the production of amylase by microorganisms using cow dung as the low cost medium.