Enhancing Extracellular Production of Recombinant α-Amylase in Escherichia coli through Co-Expression with Cutinase and Optimizing Fermentation Conditions

Abstract:

The thermostability and catalytic efficiency of Bacillus licheniformis α-amylase have been improved at high temperature and acidic conditions using site-directed mutations in our previous study. To achieve highly efficient extracellular production of this mutant α-amylase，the Bacillus licheniformis α-amylase was co-expressed with Thermobifida fusca cutinase in Escherichia coli and the induction strategy was also optimized. First，the co-expression system was compared with individual expression system，which expressed α-amylase individually，in shake flask and fermenter. The results showed that co-expression system has advantages over individual expression system in extracellular production of α-amylase. Then，the extracellular production of recombinant α-amylase in co-expression system was optimized using different induction strategies. Using the optimal induction strategy of 32 ℃ and combined use of 0.15 μmol/L IPTG and 0.5 g/（L·h） lactose，the co-expression system achieved a maximum extracellular α-amylase activity of 6.05×104 U/mL（8.92 g/L） at 32 h，which was 28.3 fold to that of achieved by individual expression system in shake flask. In addition，the extracellular α-amylase activity occupied 93.2% of total α-amylase activity.