title: Reduction of hydrogen peroxide stress derived from fatty acid beta-oxidation improves fatty acid utilization in Escherichia coli.
abstract: Fatty acids are a promising raw material for substance production because of their highly reduced and anhydrous nature, which can provide higher fermentation yields than sugars. However, they are insoluble in water and are poorly utilized by microbes in industrial fermentation production. We used fatty acids as raw materials for L-lysine fermentation by emulsification and improved the limited fatty acid-utilization ability of Escherichia coli. We obtained a fatty acid-utilizing mutant strain by laboratory evolution and demonstrated that it expressed lower levels of an oxidative-stress marker than wild type. The intracellular hydrogen peroxide (H₂O₂) concentration of a fatty acid-utilizing wild-type E. coli strain was higher than that of a glucose-utilizing wild-type E. coli strain. The novel mutation rpsA(D210Y) identified in our fatty acid-utilizing mutant strain enabled us to promote cell growth, fatty-acid utilization, and L-lysine production from fatty acid. Introduction of this rpsA(D210Y) mutation into a wild-type strain resulted in lower H₂O₂ concentrations. The overexpression of superoxide dismutase (sodA) increased intracellular H₂O₂ concentrations and inhibited E. coli fatty-acid utilization, whereas overexpression of an oxidative-stress regulator (oxyS) decreased intracellular H₂O₂ concentrations and promoted E. coli fatty acid utilization and L-lysine production. Addition of the reactive oxygen species (ROS) scavenger thiourea promoted L-lysine production from fatty acids and decreased intracellular H₂O₂ concentrations. Among the ROS generated by fatty-acid β-oxidation, H₂O₂ critically affected E. coli growth and L-lysine production. This indicates that the regression of ROS stress promotes fatty acid utilization, which is beneficial for fatty acids used as raw materials in industrial production.
authors.affiliation: Process Development Laboratories, Research Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc, 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-8681, Japan, hidetaka_doi@ajinomoto.com.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Doi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakase
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Usuda
mesh_terms: D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D005227:Fatty Acids / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000633:toxicity*; D008239:Lysine / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity
chemical_list: D005227:Fatty Acids; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D008239:Lysine