Leucobacter ruminantium sp. nov., isolated from the bovine rumen.

A Gram-stain-positive, lemon yellow-pigmented, non-motile, rod-shaped bacterium, designated strain A2T, was isolated from the rumen of cow. Cells were catalase-positive and weakly oxidase-positive. Growth of strain A2T was observed at 25-45 °C (optimum, 37-40 °C), at pH 5.5-9.5 (optimum, pH 7.5) and in the presence of 0-3.5 % (w/v) NaCl (optimum, 1 %). Strain A2T contained iso-C16 : 0 and anteiso-C15 : 0 as the major cellular fatty acids. Menaquinone-11 was detected as the sole respiratory quinone. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain A2T formed a distinct phyletic lineage within the genus Leucobacter. Strain A2T was most closely related to 'Leucobacter margaritiformis' A23 (97.7 % 16S rRNA gene sequence similarity) and Leucobacter tardus K 70/01T (97.2 %). The major polar lipids of strain A2T were diphosphatidylglycerol, phosphatidylglycerol and an unknown glycolipid. Strain A2T contained a B-type cross-linked peptidoglycan based on 2,4-diaminobutyric acid as the diagnostic diamino acid with threonine, glycine, alanine and glutamic acid but lacking 4-aminobutyric acid. The G+C content of the genomic DNA was 67.0 %. From the phenotypic, chemotaxonomic and molecular features, strain A2T was considered to represent a novel species of the genus Leucobacter, for which the name Leucobacter ruminantium sp. nov. is proposed. The type strain is A2T (=KACC 17571T=JCM 19316T).