title: Identification and characterization of a novel 2,3-butanediol dehydrogenase/acetoin reductase from Corynebacterium crenatum SYPA5-5.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhao
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Rao
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: T
authors.initials: T
authors.lastname: Bao
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.affiliation: The Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu, China.
authors.forename: T
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Chemical Engineering, Ohio State University, Columbus, OH, USA.
authors.forename: S
authors.initials: S
authors.lastname: Yang
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D002072:Butylene Glycols / Q000378:metabolism*; D003001:Cloning, Molecular; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002072:Butylene Glycols; C026978:2,3-butylene glycol; D000093:Acetoin; D000429:Alcohol Oxidoreductases; C019801:butanediol dehydrogenase
keywords: 2,3-butanediol dehydrogenase; Corynebacterium crenatum SYPA5-5; acetoin reductase; characterization; expression