Asprobacter aquaticus gen. nov., sp. nov., a prosthecate alphaproteobacterium isolated from fresh water.

A novel Gram-negative bacterium strain, DRW22-8, was isolated from fresh water taken at a depth of 22 m at Daechung Reservoir, Republic of Korea. The cells of strain DRW22-8 were aerobic and motile with a single polar flagellum or non-motile (stalked), and formed creamy-white colonies on R2A agar. The phylogenetic analysis based on 16S rRNA gene sequencing indicated that the strain formed a separate lineage within the order Rhodobacterales, showing similarity values under 91.8 % with its closest phylogenetic neighbours, Hirschia litorea, Hirschia baltica and Hirschia maritima. The chemotaxonomic results showed Q-10 as the predominant respiratory ubiquinone, three unidentified glycolipids, an unidentified lipid and phosphatidylglycerol as the major polar lipids, and C16 : 0, 11-methyl C18 : 1, C18 : 1 ω7c and/or C18 : 1 ω6c as the major fatty acids. The DNA G+C content was 64.4 mol%. The combined genotypic and phenotypic data showed that strain DRW22-8 could be distinguished from all genera within the family Hyphomonadaceae and represented a novel genus, Asprobacter gen. nov., with the name Asprobacter aquaticus sp. nov., in the family Hyphomonadaceae. The type strain is DRW22-8 (=KCTC 42356=JCM 30469).