期刊
PROCESS BIOCHEMISTRY
卷 41, 期 10, 页码 2160-2169出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.procbio.2006.06.012
关键词
glycerol metabolism; glycerol dehydratase; 1,3-propanediol oxidoreductase; 3-hydroxypropionaldehyde; DhaR; Klebsiella pneumoniae
Glycerol dehydratase that catalyses the conversion of glycerol to 3-hydroxypropionaldehyde was previously supposed to be a limiting step in the 1,3-propanediol production from glycerol. In this study, glycerol dehydratase was over-expressed separately or coordinately with 1,3-propanediol oxidoreductase in Klebsiella pneumoniae DSM2026 to investigate its effects on the glycerol fermentation. The overexpression of glycerol dehydratase surprisingly led to a serious impairment of growth of K pneumoniae in both continuous and batch cultures. Instability of the plasmids bearing the genes encoding glycerol dehydratase and/or 1,3-propanediol oxidoreductase was observed in recombinant cells, especially in anaerobic cultures using glycerol as sole carbon source. It is postulated that an imbalanced conversion of glycerol to the intermediate 3-hydroxypropionaldehyde and its further conversion to 1,3-propanediol and the associated accumulation and toxicity of 3-hydroxypropionaldehyde are responsible for the phenomena observed. Furthermore, the putative regulatory gene dhaR of the dha regulon was also overexpressed in K. pneumoniae. The increased expression of 1,3-propanediol oxidoreductase confirmed the role of DhaR as a positive regulator of the dhaT gene. (c) 2006 Elsevier Ltd. All rights reserved.
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