A bacterial strain, designated H-5T, was isolated from an artificial reservoir in Taiwan and characterized using a polyphasic taxonomic approach. Cells of strain H-5T were Gram-stain-negative, aerobic, motile by means of a single polar flagellum, rod-shaped, covered by large capsules and formed white colonies. Growth occurred at 15-30 °C (optimum, 25 °C), at pH 6-8 (optimum, pH 7) and with 0-0.5 % NaCl (optimum, 0 %). Phylogenetic analyses based on the 16S rRNA gene, the methanol dehydrogenase gene and the coding sequences of 92 protein clusters indicated that strain H-5T was affiliated with genera in the family Methylophilaceae in the class Betaproteobacteria. Strain H-5T was most closely related to Methylobacillus methanolivorans ZT with a 95.0 % 16S rRNA gene sequence similarity. Strain H-5T showed less than 73.7 % average nucleotide identity and less than 23.6 % digital DNA-DNA hybridization identity compared to the strains of related genera within the family Methylophilaceae. The predominant fatty acids were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The major isoprenoid quinone was Q-8 and the DNA G+C content was 58.3 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, one uncharacterized aminophospholipid, one uncharacterized phospholipid and one uncharacterized lipid. On the basis of the genotypic and phenotypic data presented here, strain H-5T represents a novel species of a new genus in the family Methylophilaceae, for which the name Pseudomethylobacillus aquaticus gen. nov., sp. nov. is proposed. The type strain is H-5T (=BCRC 81154T=KCTC 62865T).
Keywords: Betaproteobacteria; Methylophilaceae; Methylophilales; Pseudomethylobacillus aquaticus.