title: Synthesis of pure meso-2,3-butanediol from crude glycerol using an engineered metabolic pathway in Escherichia coli.
abstract: meso-2,3-Butanediol (meso-2,3-BDO) is essential for the synthesis of various economically valuable biosynthetic products; however, the production of meso-2,3-BDO from expensive carbon sources is an obstacle for industrial applications. In this study, genes involved in the synthesis of 2,3-BDO in Klebsiella pneumoniae were identified and used to genetically modify Escherichia coli for meso-2,3-BDO production. Two 2,3-BDO biosynthesis genes-budA, encoding acetolactate, and meso-budC, encoding meso-SADH-from K. pneumoniae were cloned into the pUC18 plasmid and introduced into E. coli. In 2 l batch culture, the SGSB03 E. coli strain yielded meso-2,3-BDO at 0.31 g/g(glucose) (with a maximum of 15.7 g/l(culture) after 48 h) and 0.21 g/g(crude glycerol) (with a maximum of 6.9 g/l(culture) after 48 h). Batch cultures were grown under optimized conditions (aerobic, 6% carbon source, 37 °C, and initial pH 7). To find the optimal culture conditions for meso-2,3-BDO production, we evaluated the enzyme activity of meso-SADH and the whole cell conversion yield (meso-2,3-BDO/acetoin) of the E. coli SGSB02, which contains pSB02. meso-SADH showed high enzyme activity at 30-37 °C and pH 7 (30.5-41.5 U/mg of protein), and the conversion yield of SGSB02 E. coli was highest at 37-42 °C and a pH of 7 (0.25-0.28 g(                            meso-2,3-BDO)/g(acetoin)).
authors.affiliation: Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 121-742, South Korea.
authors.forename: Soojin
authors.initials: S
authors.lastname: Lee
authors.forename: Borim
authors.initials: B
authors.lastname: Kim
authors.forename: Kyungmoon
authors.initials: K
authors.lastname: Park
authors.forename: Youngsoon
authors.initials: Y
authors.lastname: Um
authors.forename: Jinwon
authors.initials: J
authors.lastname: Lee
mesh_terms: D000093:Acetoin / Q000378:metabolism; D000332:Aerobiosis; D061249:Batch Cell Culture Techniques; D002072:Butylene Glycols / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D005798:Genes, Bacterial; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids; D013696:Temperature
chemical_list: D002072:Butylene Glycols; D003470:Culture Media; C026978:2,3-butylene glycol; D000093:Acetoin; D002262:Carboxy-Lyases; C023746:acetolactate decarboxylase; D005947:Glucose; D005990:Glycerol