Stagnimonas aquatica gen. nov., sp. nov., a new member of the family Nevskiaceae isolated from a freshwater mesocosm.

A novel bacterial strain, designated THS-13, isolated from a freshwater mesocosm in Taiwan, was characterized by taking a polyphasic taxonomic approach. Cells of strain THS-13 were Gram-stain-negative, aerobic, rod-shaped, motile by means of a single polar flagellum and formed translucent white coloured colonies. Growth occurred at 20-35 °C (optimum, 25 °C), at pH 5-8 (pH 6) and with 0-2 % NaCl (1 %). Phylogenetic analyses based on 16S rRNA gene and coding sequences of 92 protein clusters revealed that the strain belonged to the family Nevskiaceae in the class Gammaproteobacteria and represented an independent taxon separated from other genera. Strain THS-13 shared low level of 16S rRNA gene sequence similarity (less than 93.0 %) to members of other genera in the family Nevskiaceae and was most closely related to Nevskia aquatilis F2-63 (92.9 %). Strain THS-13 showed less than 73.4 % average nucleotide identity and less than 23.8 % digital DNA-DNA hybridization identity compared to the type strains of related genera within the family Nevskiaceae. The predominant fatty acids were C18 : 1ω7c, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and iso-C16 : 0. The major isoprenoid quinone was Q-8 and the DNA G+C content was 67.6 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, an uncharacterized aminophospholipid, an uncharacterized phospholipid and an uncharacterized aminolipid. On the basis of the genotypic and phenotypic data, strain THS-13 represents a novel species of a new genus in the family Nevskiaceae, for which we propose the name Stagnimonas aquatica gen. nov., sp. nov. The type strain is THS-13 (=BCRC 81158=LMG 30925=KCTC 62868).