Application of statistical experimental design for optimization of novel α-amylase production by anoxybacillus species

Abstract

Anoxybacillus sp. DT3-1 is a newly isolated bacterium with amylolytic activity. The gene that encodes the α-amylase was recently cloned and expressed in E. coli system. However, the expression level was far too low to be used for further analysis. The main objective of this study is to enhance the recombinant α-amylase (ADTA) expression level extracellularly. In medium comparison, LB/amp medium was found to be the best medium to support the cell growth and extracellular ADTA production. Subsequently, three factors that affect the ADTA expression which are cells absorbance during induction, concentrations of IPTG and yeast extract were screened using 23 full factorial design. Cells absorbance during induction and IPTG concentration were found to be the significant variables that affected the ADTA production. In the consequently Central Composite Rotatable Design (CCRD), the optimized condition for maximum extracellular ADTA production was determined as OD600 nm 1.52, 0.01 mM IPTG and 0.30% (w/v) yeast extract. The extracellular ADTA production was successfully increased from 30 U in the original medium to 82.29 U.