Actinomyces ruminicola sp. nov., isolated from cattle rumen

Two obligate anaerobic bacterial strains, B71(T) and D471, were isolated from cattle rumen. The novel strains were Gram-positive and rod-shaped. The strains hydrolysed xylan and starch, fermented some mono-, di- and oligosaccharides and produced formic, acetic and lactic acids as end products from glucose. Growth of the isolates was observed at 20-55 degrees Celsius and pH 6.5-9.0. The DNA G+C contents of strains B71(T) and D471 were 68.06 and 68.26 mol%, respectively. Although the two novel strains met the genus description for Actinomyces, some phenotypic characteristics, such as optimum growth temperature, requirement for O(2) and the end products of fermentation, distinguished them from previously described members of the genus. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that the novel strains belonged to the genus Actinomyces (88.3-93.6 % sequence similarity) and formed a distinct line within the clade containing Actinomyces bovis. On the basis of these results, a novel species, Actinomyces ruminicola sp. nov., is proposed. The type strain is B71(T) (=JCM 13352(T)=CGMCC 1.5030(T)).