Applied Microbiology and Biotechnology

, Volume 87, Issue 6, pp 2247–2256

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

Applied Microbial and Cell Physiology

DOI: 10.1007/s00253-010-2706-0

Cite this article as:
Jian, J., Zhang, S., Shi, Z. et al. Appl Microbiol Biotechnol (2010) 87: 2247. doi:10.1007/s00253-010-2706-0

Abstract

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.

Keywords

PHBP(3HB-co-3HV)Escherichia coliPolyhydroxyalkanoatesMixed acid fermentationMetabolic engineering

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Protein Science Laboratory of the Ministry of Education, Department of Biology, School of Life SciencesTsinghua UniversityBeijingChina
  2. 2.Department of ChemistryUniversity of MelbourneMelbourneAustralia
  3. 3.Life Science Division, Graduate School at ShenzhenTsinghua UniversityShenzhenChina