Acidobacterium capsulatum gen. nov., sp. nov.: An acidophilic chemoorganotrophic bacterium containing menaquinone from acidic mineral environment

Abstract

Acidobacterium is proposed as a new genus for the acidophilic, chemoorganotrophic bacteria containing menaquinone isolated from acidic mineral environments.Acidobacterium capsulatum is proposed for the singleAcidobacterium species which consists of eight strains (Biogroup 5). The members of this species are gram-negative, aerobic, mesophilic, non-spore-forming, capsulated, saccharolytic, and rod-shaped bacteria. They are motile by peritrichous flagella. They can grow between pH 3.0 and 6.0, but not at pH 6.5. They give positive results in tests for esculin hydrolysis, catalase, and β-galactosidase. Oxidase and urease are negative. They can use glucose, cellobiose, starch, maltose, or β-gentiobiose as a sole carbon source, but cannot use elemental sulfur and ferrous iron as an energy source. The DNA base composition is 59.7–60.8 guanine plus cytosine (G+C) mol%. The major isoprenoid quinone is menaquinone with eight isoprene units (MK-8). The major fatty acid is 13-methyltetradecanoic acid. DNA relatedness between this species and the species ofAcidiphilium, Acidomonas, andDeinobacter was 18 to 2%. From phenotypic and chemotaxonomic characters, these member do not belong to any known taxa of gram-negative bacteria. A culture of the type strain (strain 161) has been deposited in the Japan Collection of Microorganisms as JCM 7670.