title: Metabolic engineering of Escherichia coli for efficient free fatty acid production from glycerol.
abstract: Crude glycerol, generated as waste by-product in biodiesel production process, has been considered as an important carbon source for converting to value-added bioproducts recently. Free fatty acids (FFAs) can be used as precursors for the production of biofuels or biochemicals. Microbial biosynthesis of FFAs can be achieved by introducing an acyl-acyl carrier protein thioesterase into Escherichia coli. In this study, the effect of metabolic manipulation of FFAs synthesis cycle, host genetic background and cofactor engineering on FFAs production using glycerol as feed stocks was investigated. The highest concentration of FFAs produced by the engineered stain reached 4.82g/L with the yield of 29.55% (g FFAs/g glycerol), about 83% of the maximum theoretical pathway value by the type II fatty acid synthesis pathway. In addition, crude glycerol from biodiesel plant was also used as feedstock in this study. The FFA production was 3.53g/L with a yield of 24.13%. The yield dropped slightly when crude glycerol was used as a carbon source instead of pure glycerol, while it still can reach about 68% of the maximum theoretical pathway yield.
authors.affiliation: Department of Bioengineering, Rice University, Houston, TX, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Wu
authors.affiliation: Technology Holding, Salt Lake City, UT, USA.
authors.forename: Mukund
authors.initials: M
authors.lastname: Karanjikar
authors.affiliation: Department of Bioengineering, Rice University, Houston, TX, USA; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, USA. Electronic address: ksan@rice.edu.
authors.forename: Ka-Yiu
authors.initials: KY
authors.lastname: San
mesh_terms: D003198:Computer Simulation; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000096:biosynthesis* / Q000235:genetics; D024861:Genetic Enhancement / Q000379:methods; D005990:Glycerol / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D008954:Models, Biological; D009250:NADP Transhydrogenases / Q000235:genetics / Q000378:metabolism*; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D005230:Fatty Acids, Nonesterified; D009250:NADP Transhydrogenases; D010770:Phosphotransferases; C434675:NadK protein, E coli; D005990:Glycerol
keywords: Escherichia coli; Fatty acid; Glycerol; Metabolic engineering; Redox bioavailability