期刊
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
卷 87, 期 6, 页码 2247-2256出版社
SPRINGER
DOI: 10.1007/s00253-010-2706-0
关键词
PHB; P(3HB-co-3HV); Escherichia coli; Polyhydroxyalkanoates; Mixed acid fermentation; Metabolic engineering
资金
- National High Tech 863 Grants [20071860338]
- State Basic Science Foundation 973 [2007CB707804]
- National Key Technology RD Program [20091851262]
- Tsinghua University [2009THZ01005]
A series of Escherichia coli BW25113 mutants with reduced mixed acid fermentation were constructed. Genes ackA-pta, poxB, ldhA, adhE, and pflB encoding acetate kinase, phosphate acetyltransferase, pyruvate oxidase, d-lactate dehydrogenase, acetaldehyde dehydrogenase, and pyruvate formate-lyase, respectively, were deleted successively. When grown under microaerobic condition, the mutants reduced approximately 90% acetate excretion after the deletion of genes ackA-pta and poxB. Production of lactate, ethanol, and formate was also significantly reduced after the deletion of genes ldhA, adhE, and pflB, respectively. The accumulation of biomass and poly(3-hydroxybutyrate) (PHB) were significantly enhanced after deleting the mixed acid fermentation. E. coli mutant BWapld with deletions of ackA-pta, poxB, ldhA, and adhE produced twice the cell dry weight (CDW) and 3.5 times of PHB compared with its wild-type under microaerobic conditions. E. coli mutant BWapl with deletions of ackA-pta, poxB, and ldhA also achieved nearly twice CDW and three times of PHB content in comparison to the wild-type during 48 h static cultivation. Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was observed in the mutants under static cultivation. E. coli mutant BWapld could produce approximately 50 wt.% P(3HB-co-3HV) consisting of 5 mol% of 3-hydroxyvalerate (3HV) under aerobic conditions, when the seed culture was inoculated at an appropriate time. When ackA-pta, poxB, ldhA, adhE, and pflB were deleted, E. coli mutant BWapldf accumulated over 70 wt.% P(3HB-co-3HV) consisting of 8 mol% 3HV under aerobic conditions.
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