Abstract: In order to achieve high-cell-density cultivation and high expression of recombinant E. coli BL21 producing hyperthermophilic α-amylase, the medium composition and shake flask fermentation conditions were optimized using orthogonal array design. The optimal cultivation conditions for the production of α-amylase were achieved by using a pH 6.5 medium composed of 0.5 g/L glucose and 15 g/L yeast extract and an inoculum size of 3%, and adding 0.8 mmol/L IPTG for 6 h induction after 4 h of fermentation. Under these conditions, the biomass of recombinant E. coli BL21 was increased by 1.29-fold, the α-amylase activity by 1.55-fold (reaching 8.754 U/mL) and the protein expression level by 1.24-fold compared to the pre-optimization results.

Key words: hyperthermophilic α-amylase, E. coli BL21, cultivation medium, cultivation conditions