Acetoin and 2,3-butanediol are widely used in the chemical and pharmaceutical industries. The enzyme, 2,3-butanediol dehydrogenase/acetoin reductase (2,3-BDH/AR), plays a significant role in the microbial production of acetoin and 2,3-butanediol by catalysing a reversible reaction between acetoin and 2,3-butanediol. To date, a 2,3-BDH has not been characterized from Corynebacterium crenatum. 2,3-BDH was cloned from Coryne. crenatum SYPA5-5 and expressed in Escherichia coli BL21. Sequence analysis suggested that the 2,3-BDH from Coryne. crenatum SYPA5-5 belongs to the short-chain dehydrogenase/reductase superfamily. Its maximum specific activity was obtained at 35°C, however, it became very unstable when the temperature was above 35°C. Its optimal pH was 4·0 for reduction reaction and 10·0 for oxidation reaction. The 2,3-BDH activity was increased to some extent by Ca(2+) , Mg(2+) , Zn(2+) and Mn(2+) ions. In particular, Ca(2+) induced about 1·5-fold increase. The value of kcat /Km for diacetyl and acetoin are higher than for 2,3-butanediol indicating that 2,3-BDH can easily reduce diacetyl or acetoin to 2,3-butanediol under lower pH conditions. The characteristics of 2,3-BDH from Coryne. crenatum SYPA5-5 will give guide to further studies for the production of acetoin and 2,3-butanediol with engineered Coryne. crenatum SYPA5-5.
Significance and impact of the study: Acetoin and 2,3-butanediol are commonly used as platform chemicals and widely used in pharmaceutical industries. 2,3-butanediol dehydrogenase/acetoin reductase (2,3-BDH/AR) plays a significant role in the microbial production of acetoin and 2,3-butanediol. In this study, 2,3-BDH was cloned from Corynebacterium crenatum SYPA5-5, was expressed in Escherichia coli BL21 and characterized with respect to the optimal temperature, pH, substrate specificity and kinetics. The results will guide further studies in Coryne. crenatum SYPA5-5 for the production of acetoin and 2,3-butanediol.
Keywords: 2,3-butanediol dehydrogenase; Corynebacterium crenatum SYPA5-5; acetoin reductase; characterization; expression.
© 2015 The Society for Applied Microbiology.