Production of alpha amylase from a randomly induced mutant strain of Bacillus amyloliquefaciens and its application as a desizer in textile industry

摘要

The present study is concerned with the improvement of Bacillus amyloliquefaciens strain UNG-16 for alpha amylase production. The bacterial culture was exposed to UV irradiation at 1.6×102J/m2/S for 15-60 min. However, UV induced viables did not give improved alpha amylase production; therefore chemical mutation using ethyl methane sulphonate (EMS 50-300 μl/ml) was undertaken for 10-60 min. The mutant B. amyloliquefaciens EMS-6 gave 102.78± 2.22 U/ml/min enzyme activity which was 1.4 fold higher than the parental strain. In stirred fermentor, the incubation period was reduced from 72 to 48 h after inoculation. The production of alpha amylase was found to be maximal when the 60% volume, 2.0 vvm air supply and 400 rpm agitation rate was maintained during the fermentation period. The incubation temperature (37oC) and size of inoculum (8.0 %) were also optimized. A 100% desizing of grey fabric (or starch removal) was obtained with 200-250 enzyme units at pH 6.5 at 60oC in 1 h.