Production of polyhydroxyalkanoates by Escherichia coli mutants with defected mixed acid fermentation pathways

• Published in: Applied microbiology and biotechnology 2010-08, Vol.87 (6), p.2247-2256
• Main Authors: Jian, Jia, Zhang, Shao-Qin, Shi, Zhen-Yu, Wang, Wei, Chen, Guo-Qiang, Wu, Qiong
• Format: Article
• Language: English
• Subjects: Acetaldehyde dehydrogenase; Acids; Acids - metabolism; Aerobic conditions; Applied Microbial and Cell Physiology; Biological and medical sciences; Biomedical and Life Sciences; Biosynthetic Pathways; Biotechnology; By products; Carbon; Cell growth; Composite materials; Cultivation; Dehydrogenase; Dehydrogenases; E coli; Escherichia coli; Escherichia coli - enzymology; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Ethanol; Fermentation; Fundamental and applied biological sciences. Psychology; Genes; Genetics; Glucose; Kinases; Life Sciences; Metabolic engineering; Metabolism; Metabolites; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Microbial Genetics and Genomics; Microbiology; Mixed acid fermentation; Mutants; Mutation; P(3HB-co-3HV); PHB; Plasmids; Poly-3-hydroxybutyrate; Polyhydroxyalkanoates; Polyhydroxyalkanoates - metabolism; Polyhydroxybutyrate; Studies; Trace elements
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-010-2706-0

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.