Emendation of the genus Acidomonas Urakami, Tamaoka, Suzuki and Komagata 1989

The genus Acidomonas and the species Acidomonas methanolica were recharacterized by using the type strain (NIRIC 0498(T)), three reference strains and 10 methanol-utilizing bacteria that were isolated from activated sludge from three different sewage-treatment plants in Tokyo. Based on 16S rDNA sequences, all strains formed a single cluster within the Acetobacteraceae that was clearly different from the genera Acetobacter, Gluconobacter, Gluconacetobacter, Asaia and Kozakia. The 14 strains were identified as a single species, Acidomonas methanolica, by DNA-DNA similarities, showed DNA G + C contents that ranged from 62 to 63 mol% and had Q-10 as the major quinone, accounting for >87% of total ubiquinones. Cells of Acidomonas methanolica had a single polar flagellum (or occasionally polar tuft flagella); this differs from a previous study that described peritrichous flagella. Oxidation of acetate was positive for all strains, but oxidation of lactate was weakly positive and varied with strains. Dihydroxyacetone was not produced from glycerol. Pantothenic acid was an essential requirement for growth. The strains tested grew at mostly the same extent at pH 3.0-8.0. Therefore, Acidomonas methanolica should be regarded as acidotolerant, not aciclophilic. The descriptions of the genus Acidomonas and the species Acidomonas methanolica Urakami, Tamaoka, Suzuki and Komagata 1989 are emended with newly obtained data.