ISOLATION AND IDENTIFICATION OF A STRAIN PRODUCING ACID STABLE α-AMYLASE AND ITS FERMENTATION CONDITIONS

A high-yield acid-resistant α-amylase strain was screened from soil samples from starch factory and sugar factor through trypan-blue method.The strain,named as xm-1,was identified as Bacillus subtilis by means of physiological-biochemical characterization as well as 16S rDNA sequencing.The optimal enzyme production temperature of the strain was 37 ℃,the optimal enzyme production time is the 13th hour after fermentation,and there were no significant effects of liquid volume on the enzyme production of the stain.The highest enzyme activity under the optimal condition was up to 242 U/mL.