Objective:An amylase-producing strain was screened and identified from mangrove soil in Shijiao Mangrove Nature Reserve of Guangxi.The amylase-producing process was optimized by Plackett-Burman de-sign and response surface optimization,in order to establish the fermentation process of high amylase production.Methods:The amylase-producing strain was obtained from mangrove soil by plate screening.The strain was identified by physiological,biochemical and 16S rDNA sequencing.The optimized condition for enzyme produc-tion was obtained by single factor optimization,Plackett-Burman design and response surface optimization.Re-sults:The amylase-producing strain was obtained from mangrove soil.Bacillus velezensis was identified and named Bacillus velezensis MG5-8.The optimum temperature and pH of the amylase were 70℃and 6.0,respec-tively.The optimum temperature for amylase production was 30℃,the optimum carbon source for amylase pro-duction was corn steep liquor powder,and the optimum nitrogen source was soybean powder and beef extract by single factor optimization.The optimum enzyme production conditions were as following:soybean powder 0.51%,beef extract 0.55%,corn steep liquor powder 0.34%.Under these conditions,the theoretical maximum en-zyme activity of this strain was 134.03 U/mL.The activity of B.velezensis MG5-8 amylase was 130.28 U/mL,which was 97.2%of the theoretical value and 5.63 folds of the enzyme activity before optimization.Conclusion:A strain producing amylase(B.velezensis MG5-8)is successfully isolated and identified.The maximum enzyme activity is 130.28 U/mL after optimization.
维普
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