title: Modification of β-oxidation pathway in Ralstonia eutropha for production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from soybean oil.
abstract: Ralstonia eutropha H16 is a useful platform for metabolic engineering aiming at efficient production of polyhydroxyalkanaotes being attracted as practical bioplastics. This study focused on bifunctional (S)-specific 2-enoyl-CoA hydratase/(S)-3-hydroxyacyl-CoA dehydrogenase encoded by fadB to obtain information regarding β-oxidation in this bacterium and to achieve compositional regulation of poly((R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate) [P(3HB-co-3HHx)] synthesized from soybean oil. In addition to two FadB homologs (FadB1 and FadB') encoded within the previously identified β-oxidation gene clusters on the chromosome 1, a gene of third homolog (FadB2) was found on chromosome 2 of R. eutropha. The fadB homologs were disrupted in R. eutropha strain NSDG expressing a mutant gene of PHA synthase from Aeromonas caviae. The gene disruptions affected neither growth nor PHA production on fructose. On soybean oil, fadB' deletion led to reduction of PHA quantity attributed to decrease of 3HB unit, while fadB1 deletion slightly increased 3HHx composition without serious negative impact on both cell growth and PHA biosynthesis. Double deletion of fadB1 and fadB' significantly impaired the cell growth and PHA biosynthesis, indicating the major roles of fadB1 and fadB' in β-oxidation. When fadB1 was deleted in several engineered strains of R. eutropha possessing additional (R)-enoyl-CoA hydratase gene(s), the net amounts of 3HHx unit in the PHA fractions showed 6-21% increase probably due to slightly enhanced supply of medium-chain-length 2-enoyl-CoAs through the partially impaired β-oxidation. These results demonstrated that modification of β-oxidation by fadB1 deletion was effective for increasing 3HHx composition in the copolyesters produced from soybean oil.
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Chayatip
authors.initials: C
authors.lastname: Insomphun
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Mifune
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Orita
authors.affiliation: Enzyme Research Team, RIKEN Biomass Engineering Program, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Numata
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan. Electronic address: tfukui@bio.titech.ac.jp.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Fukui
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000096:biosynthesis* / Q000378:metabolism; D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D002208:Caproates / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004746:Enoyl-CoA Hydratase / Q000235:genetics; D005632:Fructose / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial / Q000235:genetics; D010084:Oxidation-Reduction; D013024:Soybean Oil / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D020155:3-Hydroxybutyric Acid; D000217:Acyltransferases; D002208:Caproates; D004746:Enoyl-CoA Hydratase; D005632:Fructose; D013024:Soybean Oil; C115940:poly(3-hydroxybutyrate-co-3-hydroxyhexanoate); D000094122:Polyhydroxybutyrates; C077225:poly(3-hydroxyalkanoic acid) synthase; C406162:R-specific trans-2,3-enoylacyl-CoA hydratase
keywords: Bioplastic; Polyhydroxyalkanoate; Ralstonia eutropha; Vegetable oil; β-Oxidation