Mutagenesis of Bacillus Licheniformis through Ethyl Methanesulfonate for Alpha Amylase Production

The present study is concerned with the improvement of Bacillus licheniformis strain GCB30 for alpha amylase production in 250 ml Erlenmeyer flasks. Chemical mutation using ethyl methanesulfonate (EMS 50-300 μ/ml) was undertaken for 10-60 min. Twenty eight isolates were selected on the basis of clear zones of starch hydrolysis. Only one isolate designated as B. licheniformis EMS-200 gave 102.78±2.01 U/ml/min enzyme activity. The enzyme production was found to be maximal when fermentation medium containing (g/l) lactose 10.0, bactopeptone 14.0, yeast extract 6.0, KCl 1.0, CaCl2 0.25, MgCl2 0.2, MnSO4 0.001, FeSO4 0.0005, pH 6.5 was incubated at 37C for 72 h. The volume of medium (50 ml) and size of inoculum (4.0 %) were also optimized. The optimal enzyme activity was determined as a function of buffer pH (7.0) and temperature (60oC).