title: Enhancing fatty acid production in Escherichia coli by Vitreoscilla hemoglobin overexpression.
abstract: Our recent13C-metabolic flux analysis (13C-MFA) study indicates that energy metabolism becomes a rate-limiting factor for fatty acid overproduction in E. coli strains (after "Push-Pull-Block" based genetic modifications). To resolve this bottleneck, Vitreoscilla hemoglobin (VHb, a membrane protein facilitating O2transport) was introduced into a fatty-acid-producing strain to promote oxygen supply and energy metabolism. The resulting strain, FAV50, achieved 70% percent higher fatty acid titer than the parent strain in micro-aerobic shake tube cultures. In high cell-density bioreactor fermentations, FAV50 achieved free fatty acids at a titer of 7.02 g/L (51% of the theoretical yield). In addition to "Push-Pull-Block-Power" strategies, our experiments and flux balance analysis also revealed the fatty acid over-producing strain is sensitive to metabolic burden and oxygen influx, and thus a careful evaluation of the cost-benefit tradeoff with the guidance of fluxome analysis will be fundamental for the rational design of synthetic biology strains. Biotechnol. Bioeng. 2017;114: 463-467. © 2016 Wiley Periodicals, Inc.
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130.
authors: Di
authors: D
authors: Liu
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130.
authors: Ni
authors: N
authors: Wan
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130.
authors: Fuzhong
authors: F
authors: Zhang
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130.
authors: Yinjie J
authors: YJ
authors: Tang
authors: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri, 63130.
authors: Stephen G
authors: SG
authors: Wu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D004734:Energy Metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism*; D005285:Fermentation; D060847:Metabolic Engineering / Q000379:methods*; D064688:Metabolic Flux Analysis; D010100:Oxygen / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics* / Q000378:metabolism; D058615:Synthetic Biology; D054793:Truncated Hemoglobins / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; D011994:Recombinant Proteins; D054793:Truncated Hemoglobins; C082613:hemoglobin protein, Vitreoscilla; D010100:Oxygen
keywords: energy metabolism; flux balance analysis; metabolic burden; oxygen uptake; synthetic biology