title: Azonexus hydrophilus sp. nov., a nifH gene-harbouring bacterium isolated from freshwater.
abstract: Three Gram-negative, non-pigmented, rod-shaped, facultatively aerobic bacterial strains, designated d8-1T, d8-2 and IMCC1716, were isolated from a freshwater spring sample and a eutrophic freshwater pond. Based on characterization using a polyphasic approach, the three strains showed highly similar phenotypic, physiological and genetic characteristics. All of the strains harboured the nitrogenase gene nifH, but nitrogen-fixing activities could not be detected in nitrogen-free culture media. The three strains shared 99.6-99.7 % 16S rRNA gene sequence similarity and showed 89-100 % DNA-DNA relatedness, suggesting that they represent a single genomic species. Phylogenetic analysis based on 16S rRNA gene sequences showed that strains d8-1T, d8-2 and IMCC1716 formed a monophyletic branch in the periphery of the evolutionary radiation occupied by the genus Azonexus. Their closest neighbours were Azonexus caeni Slu-05T (96.7-96.8 % similarity) and Azonexus fungiphilus BS5-8T (96.3-96.6 %). The DNA-DNA relatedness of the novel strains to these two species of the genus Azonexus was less than 70 %. The isolates could also be differentiated from recognized members of the genus Azonexus on the basis of phenotypic and biochemical characteristics. It is evident, therefore, that the three strains represent a novel species of the genus Azonexus, for which the name Azonexus hydrophilus sp. nov. is proposed. The type strain is d8-1T (=LMG 24005T=BCRC 17657T).
authors.affiliation: Department of Soil and Environmental Sciences, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Jui-Hsing
authors.initials: JH
authors.lastname: Chou
authors.forename: Sing-Rong
authors.initials: SR
authors.lastname: Jiang
authors.forename: Jang-Cheon
authors.initials: JC
authors.lastname: Cho
authors.forename: Jaeho
authors.initials: J
authors.lastname: Song
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Lin
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Chen
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D005618:Fresh Water / Q000382:microbiology; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics*; D010641:Phenotype; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D043362:Rhodocyclaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D013045:Species Specificity; D013624:Taiwan; D009626:Terminology as Topic
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; C029130:nitrogenase reductase