Isolation And Characterization Of Thermostable And Acid-stable α-Amylase Producing Strain Bacillales Bacterium. SF-8

α-amylase can hydrolyze the starch.α-amylases are widely applied in numerous areas,such as starch saccharification,fermentation,spin,paper. The action ofα-amylase in low-pH leads to a rapid decrease of the starch solution viscosity.Thus any research onα-amylase is particularly significant in both industrial production and scientific investigation.A new thermostable and acid-stableα-amylase producing strain was isolated from the soil of Hangzhou and identified as Bacillales bacterium. SF-8 by 16s rDNA.The maximum activity ofα-amylase produced by SF-8 was 6440 U/ml（60℃,pH5.0）The fermentation medium and culture condition of the strain were investigated,and the amylase activity was changed from 672 U/ml to 6440 U/ml.The pH optimum for the amylase is 5.0,and the optimal temperature for the activity of enzyme is 60℃.This amylase was stable to high temperature,66%of enzyme activity was retained when disposed at 60℃for 100 min.After stored at 4℃for 10 days,it still has 57%of activity.The presence or absence of Ca²⁺,Fe²⁺,Mg²⁺and Mn²⁺did not affect its enzyme activity and thermal stability.The enzyme activity stain experiment indicated the enzyme was approximately 60kDa.It is meaningful to further study the characterizations of this stain for the application in industry.