Aquincola amnicola sp. nov., isolated from a freshwater river.

Strain TTM-94, isolated from a water sample taken from the Caohu River in Taiwan, was characterized using a polyphasic taxonomic approach. Cells of strain TTM-94 were Gram-staining-negative, aerobic, poly-β-hydroxybutyrate-accumulating, motile by a single polar flagellum, short rod-shaped and surrounded by a thick capsule and it formed cream colored colonies. Growth occurred at 20-30 °C (optimum, 30 °C), at pH 6.0-8.0 (optimum, pH 6.0), and in the presence of 0-2% NaCl (optimum 0.5%). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain TTM-94 belonged to the genus Aquincola in the Rubrivivax-Roseateles-Leptothrix-Ideonella-Aquabacterium branch of the class Betaproteobacteria and its most closely related neighbour was Aquincola tertiaricarbonis L10 with sequence similarity of 97.0%. Strain TTM-94 contained summed feature 3 (comprising Cω7c and/or Cω6c), C and Cω7c as the predominant fatty acids. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several uncharacterized lipids. The major respiratory quinone was Q-8. Genomic DNA G + C content of strain TTM-94 was 70.7 mol%. Strain TTM-94 exhibited less than 30% DNA-DNA relatedness with A. tertiaricarbonis L10. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain TTM-94 should be classified as a novel species of the genus Aquincola, for which the name Aquincola amnicola sp. nov. is presented. The type strain is TTM-94 (= BCRC 80890 = LMG 28709).