title: R-acetoin accumulation and dissimilation in Klebsiella pneumoniae.
abstract: Klebsiella pneumoniae is a 2,3-butanediol producer, and R-acetoin is an intermediate of 2,3-butanediol production. R-acetoin accumulation and dissimilation in K. pneumoniae was studied here. A budC mutant, which has lost 2,3-butanediol dehydrogenase activity, accumulated high levels of R-acetoin in culture broth. However, after glucose was exhausted, the accumulated R-acetoin could be reused by the cells as a carbon source. Acetoin dehydrogenase enzyme system, encoded by acoABCD, was responsible for R-acetoin dissimilation. acoABCD mutants lost the ability to grow on acetoin as the sole carbon source, and the acetoin accumulated could not be dissimilated. However, in the presence of another carbon source, the acetoin accumulated in broth of acoABCD mutants was converted to 2,3-butanediol. Parameters of R-acetoin production by budC mutants were optimized in batch culture. Aerobic culture and mildly acidic conditions (pH 6-6.5) favored R-acetoin accumulation. At the optimized conditions, in fed-batch fermentation, 62.3 g/L R-acetoin was produced by budC and acoABCD double mutant in 57 h culture, with an optical purity of 98.0 %, and a substrate conversion ratio of 28.7 %.
authors.affiliation: Lab of Biorefinery, Shanghai Advanced Research Institute, Chinese Academy of Sciences, No. 99 Haike Road, Pudong, Shanghai, 201210, People's Republic of China.
authors.forename: Dexin
authors.initials: D
authors.lastname: Wang
authors.forename: Jidong
authors.initials: J
authors.lastname: Zhou
authors.forename: Chuan
authors.initials: C
authors.lastname: Chen
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.forename: Jiping
authors.initials: J
authors.lastname: Shi
authors.forename: Biao
authors.initials: B
authors.lastname: Jiang
authors.forename: Pengfu
authors.initials: P
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Hao
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000094:Acetoin Dehydrogenase / Q000235:genetics / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D002072:Butylene Glycols / Q000378:metabolism; D002244:Carbon / Q000737:chemistry; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics*; D010957:Plasmids / Q000235:genetics
chemical_list: D002072:Butylene Glycols; D003470:Culture Media; C026978:2,3-butylene glycol; D002244:Carbon; D000093:Acetoin; D000094:Acetoin Dehydrogenase