Optimization of Fermentation Conditions for Production of Diacetyl Reductase Using Recombinant Escherichia coli

Abstract:

Optically pure 2，3-butanediol is one of the important building blocks. Bioreduction of diacetyl using diacetyl reductase is an environmentally friendly method for chiral 2，3-butanediol production. The medium components and induction conditions of diacetyl reductase produced by recombinant Escherichia coli were optimized in flasks. The optimal medium composition for the production of diacetyl reductase was listed as follows：glycerol 5 g/L，yeast extract 10 g/L，peptone 5 g/L，（NH4）2SO4 1.5 g/L，sodium citrate 5 g/L，KH2PO4 1 g/L，MgSO4·7H2O 0.5 g/L and NaCl 2 g/L. The optimal induction conditions were listed as follows：37 ℃ and 0.1 mmol/L IPTG. After induced for 6 h under the optimized conditions，the enzyme activities reached to 13.84 kU/g dry cell weight and 33.65 kU/L，which were 2.04 and 4.23 folds of those in basic medium，1.16 and 1.71 folds of those in LB medium. In a 3 L fermenter，under the optimized conditions，the maximum enzyme activities achieved at 14.09 kU/g and 64.62 kU/L after cultured for 8 h，which were both higher than those in flasks. This study provides useful guidance on the highly efficient preparation of diacetyl reductase by recombinant Escherichia coli for the preparation of chiral 2，3-butanediol.