Proposal of Solimonas aquatica sp. nov., reclassification of Sinobacter flavus Zhou et al. 2008 as Solimonas flava comb. nov. and Singularimonas variicoloris Friedrich and Lipski 2008 as Solimonas variicoloris comb. nov. and emended descriptions of the genus Solimonas and its type species Solimonas soli
A bacterial strain designated NAA16T was isolated from a freshwater spring in Taiwan and was characterized using a polyphasic taxonomic approach. Strain NAA16T was aerobic, Gram-staining-negative, rod-shaped, non-spore-forming and motile by means of a single polar flagellum. Growth occurred at 20–40 °C (optimum, 25 °C), at pH 7.0–8.0 (optimum, pH 7.5) and with up to 1 % NaCl (optimum, 0.5 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that the closest relatives of strain NAA16T were Singularimonas variicoloris MN28T, Sinobacter flavus CW-KD 4T and Solimonas soli DCY12T, with respective sequence similarities of 96.7, 96.6 and 96.2 %. Phylogenetic trees reconstructed from 16S rRNA gene or rpoB sequences (encoding the β-subunit of the RNA polymerase) revealed that the novel strain NAA16T and these three closest relatives formed an independent phylogenetic clade within the Gammaproteobacteria. Strain NAA16T contained C16 : 0, C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) as predominant fatty acids and possessed phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an uncharacterized aminophospholipid as dominant polar lipids. The major isoprenoid quinone was Q-8. The DNA G+C content of strain NAA16T was 66.2 mol%. The taxonomic relationship of strain NAA16T, Singularimonas variicoloris DSM 15731T, Sinobacter flavus DSM 18980T and Solimonas soli LMG 24014T was clarified by means of a direct experimental comparison. Based on phenotypic, chemotaxonomic and phylogenetic data, the descriptions of the genus Solimonas and its type species Solimonas soli are emended. Members of the genus are Gram-negative, oxidase- and catalase-positive, aerobic or facultatively anaerobic and chemo-organotrophic. Chemotaxonomically, members of the genus Solimonas possess Q-8 as the major respiratory quinone, C16 : 0 and C18 : 1ω7c as predominant fatty acids and phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an uncharacterized aminophospholipid as dominant polar lipids; the DNA G+C content is 64.9–68.4 mol%. Phylogenetic evidence, supported by chemotaxonomic and phenotypic data, allowed us to assign strain NAA16T to the genus Solimonas within the novel species Solimonas aquatica sp. nov. (type strain NAA16T = BCRC 17835T = LMG 24500T). The reclassification of Sinobacter flavus as Solimonas flava comb. nov. (type strain CW-KD 4T = DSM 18980T = KCTC 12881T = CCTCC AB 206145T) and Singularimonas variicoloris as Solimonas variicoloris comb. nov. (type strain MN28T = DSM 15731T = LMG 22844T) is also proposed.