Acidocella aquatica sp. nov., a novel acidophilic heterotrophic bacterium isolated from a freshwater lake.

A novel acidophilic heterotrophic bacterium, strain Ok2G, was isolated from a freshwater lake in Japan. Cells of the isolate were Gram-stain-negative and non-motile rods (0.6-0.8×1.0-2.8 µm). Growth was observed at 4-35 °C with an optimum growth temperature of 28 °C. The pH range for growth was 3.0-6.2 with an optimum pH of 4.5. The strain utilized fructose, glucose, sucrose, mannitol, sorbitol, ethanol, benzyl alcohol, pyruvate, yeast extract and tryptone as carbon and energy sources for aerobic growth. DNA G+C content was 62.6 mol%. The major cellular fatty acid and the isoprenoid quinone were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and Q-10, respectively. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain Ok2G belongs to the genus Acidocella but is distinct from existing species with sequence similarities lower than 97 %. On the basis of these results, strain Ok2G (=NBRC 112502=DSM 104037) is proposed as the type strain of a novel species, Acidocellaaquatica sp. nov.