NDLI: Overexpression of NAD kinase in recombinant Escherichia coli harboring the phbCAB operon improves poly(3-hydroxybutyrate) production

Content Provider	Springer Nature Link
Author	Li, Zheng Jun Cai, Lei Wu, Qiong Chen, Guo Qiang
Copyright Year	2009
Abstract	NAD kinase was overexpressed to enhance the accumulation of poly(3-hydroxybutyrate) (PHB) in recombinant Escherichia coli harboring PHB synthesis pathway via an accelerated supply of NADPH, which is one of the most crucial factors influencing PHB production. A high copy number expression plasmid pE76 led to a stronger NAD kinase activity than that brought about by the low copy number plasmid pELRY. Overexpressing NAD kinase in recombinant E. coli was found not to have a negative effect on cell growth in the absence of PHB synthesis. Shake flask experiments demonstrated that excess NAD kinase in E. coli harboring the PHB synthesis operon could increase the accumulation of PHB to 16–35 wt.% compared with the controls; meanwhile, NADP concentration was enhanced threefold to sixfold. Although the two NAD kinase overexpression recombinants exhibited large disparity on NAD kinase activity, their influence on cell growth and PHB accumulation was not proportional. Under the same growth conditions without process optimization, the NAD kinase-overexpressing recombinant produced 14 g/L PHB compared with 7 g/L produced by the control in a 28-h fermentor study. In addition, substrate to PHB yield Y PHB/glucose showed an increase from 0.08 g PHB/g glucose for the control to 0.15 g PHB/g glucose for the NAD kinase-overexpressing strain, a 76% increase for the Y PHB/glucose. These results clearly showed that the overexpression of NAD kinase could be used to enhance the PHB synthesis.
Starting Page	939
Ending Page	947
Page Count	9
File Format	PDF
ISSN	01757598
Journal	Applied Microbiology and Biotechnology
Volume Number	83
Issue Number	5
e-ISSN	14320614
Language	English
Publisher	Springer-Verlag
Publisher Date	2009-04-09
Publisher Place	Berlin, Heidelberg
Access Restriction	Subscribed
Subject Keyword	PHB Polyhydroxyalkanoates Cofactor engineering NAD kinase NADPH E. coli Microbial Genetics and Genomics Microbiology Biotechnology
Content Type	Text
Resource Type	Article
Subject	Medicine Applied Microbiology and Biotechnology Biotechnology

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