Mutagenic Breeding Strain Of Producing Acid A-amylase By UV

The industry that processes starch of raw materials advances by leaps and bounds. A lot of fields in deep processing of raw material of starch need acid-resistantα-amylase which can act on starch under low pH condition。Application of acid-α-amylase improve on industrial art of starch processing, reduce raw material consumption, increase utilization rate of industrial scrap; therefore acid-resistantα-amylase apply wildly on numerous field,such as fermentation、feed、food-stuff and bio-pharmacy industry。Our lab had screen a strain of Bacillus amyloliquefaciens B-5.The amylase of producing by Bacillus amyloliquefaciens B-5 has an optimum pH of 5.0 and an optimum temperature of 70℃, and has ability of breaking down raw-starch. This strain has low ability of yielding acidα-amylase.In this study The condition of preparing protoplast was optimized. The strain of Bacillus amyloliquefaciens B-5 was mutated by UV. The 2500 ratios of see-through circle diameter to colony diameter was estimated roughly .The 200 strains of greater ratio were fermented in flask. The 40 strains were chosen from the 200 strains The 10 strains which had better ability of producing acidα-amylase had been screened out from the 40 strains. The number of UV-329 which was measured acidα-amylase activity has the most yield of producing acidα-amylase.The acidα-amylase was produced by mutant strain UV-329 ,the optimal pH was 5.5 and the optimum of temperature was 50℃.It was checked by SDS-PAGE and Native-PAGE. The acidα-amylase of UV-329 was different from the acidα-amylase of B-5, The acidα-amylase of UV-329’moleculer weight is 62.8KDa, the acidα-amylase of B-5 is 47.5KDa.