Applied Biochemistry and Biotechnology, Vol.180, No.1, 136-151, 2016
Characterization and Optimization of Amylase Production in WangLB, a High Amylase-Producing Strain of Bacillus
The costs of amylase represent ca. 24 % of the expenditures in the starch industry and an increase in amylase production and/or activity will greatly cut down on production costs. In the present study, we obtained a high amylase-producing strain of bacteria, WangLB, and identified it as a member of the Bacillus genus based on 16S rDNA analysis. The fermentation conditions for amylase production in the strain were optimized, and the maximum amylase activity we obtained was 26,670 +/- 1390 U/mL, under the optimized conditions of 48-h incubation in liquid starch medium, 35 A degrees C, pH 10, 1 % v/v inoculum concentration, 20 g/L starch concentration, and 0.1 % w/v peptone. The influences of 16 small organic inducers on amylase production were tested, and the results showed that 20 mmol/L alanine greatly enhanced amylase production to 290 % of the baseline level. We also conducted an amylase enzymology analysis. The molecular weight of the amylase was 55 kD, determined by SDS-PAGE. The optimum temperature and pH for the amylase were 55 A degrees C and pH 9, respectively. The enzyme also showed high activity over a wide range of temperatures (50-85 A degrees C) and pH values (3-10), and the activity of the amylase was Ca2+ independent. The kinetic parameters K (m) and V (max) were 0.37 +/- 0.02 mg/mL and 233 U/mg, respectively. Finally, the amylase was applied to the hydrolysis of five different brands of starch. It was found that the hydrolyzability of the substrate by amylase increased along with starch solubility.