title: Taxonomic characterization and metabolic analysis of the Halomonas sp. KM-1, a highly bioplastic poly(3-hydroxybutyrate)-producing bacterium.
abstract: In a brief previous report, the gram-negative moderately halophilic bacterium, Halomonas sp. KM-1, that was isolated in our laboratory was shown to produce the bioplastic, poly(3-hydroxybutyrate) (PHB), using biodiesel waste glycerol (Kawata and Aiba, Biosci. Biotechnol. Biochem., 74, 175-177, 2010). Here, we further characterized this KM-1 strain and compared it to other Halomonas strains. Strain KM-1 was subjected to a polyphasic taxonomic study. Strain KM-1 was rod-shaped and formed colonies on a plate that were cream-beige in color, smooth, opaque, and circular with entire edges. KM-1 grew under environmental conditions of 0.1%-10% (w/v) NaCl, pH 6.5-10.5 and at temperatures between 10°C and 45°C. The G+C content of strain KM-1 was 63.9 mol%. Of the 16 Halomonas strains examined in this study, the strain KM-1 exhibited the highest production of PHB (63.6%, w/v) in SOT medium supplemented with 10% glycerol, 10.0 g/L sodium nitrate and 2.0 g/L dipotassium hydrogen phosphate. The intracellular structures within which PHB accumulated had the appearance of intracellular granules with a diameter of approximately 0.5 μm, as assessed by electron microscopy. The intra- and extra-cellular metabolites of strain KM-1 were analyzed by capillary electrophoresis mass spectrometry. In spite of the high amount of PHB stored intra-cellularly, as possible precursors for PHB only a small quantity of 3-hydroxybutyric acid and acetyl CoA, and no quantity of 3-hydroxybutyl CoA, acetoacetyl CoA and acetoacetate were detected either intra- or extra-cellularly, suggesting highly efficient conversion of these precursors to PHB.
authors.affiliation: Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Midorigaoka, Ikeda, Osaka 563-8577, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kawata
authors.forename: Lian-Hua
authors.initials: LH
authors.lastname: Shi
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kawasaki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shigeri
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D005990:Glycerol / Q000378:metabolism; D020632:Halomonas / Q000145:classification* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D006885:Hydroxybutyrates / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010802:Phylogeny; D011091:Polyesters / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D000094122:Polyhydroxybutyrates
chemical_list: D004269:DNA, Bacterial; D005990:Glycerol; D006885:Hydroxybutyrates; D011091:Polyesters; D012336:RNA, Ribosomal, 16S; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates