title: Overproduction of free fatty acids in E. coli: implications for biodiesel production.
abstract: Whereas microbial fermentation processes for producing ethanol and related alcohol biofuels are well established, biodiesel (methyl esters of fatty acids) is exclusively derived from plant oils. Slow cycle times for engineering oilseed metabolism and the excessive accumulation of glycerol as a byproduct are two major drawbacks of deriving biodiesel from plants. Although most bacteria produce fatty acids as cell envelope precursors, the biosynthesis of fatty acids is tightly regulated at multiple levels. By introducing four distinct genetic changes into the E. coli genome, we have engineered an efficient producer of fatty acids. Under fed-batch, defined media fermentation conditions, 2.5 g/L fatty acids were produced by this metabolically engineered E. coli strain, with a specific productivity of 0.024 g/h/g dry cell mass and a peak conversion efficiency of 4.8% of the carbon source into fatty acid products. At least 50% of the fatty acids produced were present in the free acid form.
authors.affiliation: Department of Chemistry, Stanford University, Stanford CA 94305, USA.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Lu
authors.forename: Harmit
authors.initials: H
authors.lastname: Vora
authors.forename: Chaitan
authors.initials: C
authors.lastname: Khosla
mesh_terms: D020001:1-Butanol / Q000378:metabolism*; D001674:Bioelectric Energy Sources; D019149:Bioreactors / Q000382:microbiology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000235:genetics* / Q000378:metabolism*; D005742:Gasoline / Q000382:microbiology*; D005818:Genetic Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; D005230:Fatty Acids, Nonesterified; D005742:Gasoline; D011994:Recombinant Proteins; D020001:1-Butanol