16S RIBOSOMAL DNA-SEQUENCES OF ANAEROBIC COCCI AND PROPOSAL OF RUMINOCOCCUS-HANSENII COMB-NOV AND RUMINOCOCCUS-PRODUCTUS COMB-NOV

The 16S ribosomal DNA sequences of representative members of the family Peptococcaceae were determined. The members of the family examined were divided into the following four phylogenetic groups: Peptococcus niger ATCC 27731T (T = type strain), the Sarcina-Peptostreptococcus anaerobius group, the ruminococcus-coprococcus group, and the peptostreptococcus group. Peptococcus niger, the type species of the family, was not related to other members of the family. Peptostreptococcus anaerobius ATCC 27337T, the type strain of the type species of the genus Peptostreptococcus, was closely related to Clostridium sordellii NCIB 10717T (level of sequence similarity, 85%). Sarcina ventriculi GIFU 7886, a spore-forming anaerobic gram-positive coccus, clustered with Clostridium perfringens ATCC 13124T at a similarity value of 91%. Members of the Sarcina-Peptostreptococcus anaerobius group clustered with clostridia at similarity values ranging from 85 to 91%. The type strains of Peptostreptococcus prevotii, Peptostreptococcus asaccharolyticus, Peptostreptococcus micros, and Peptostreptococcus magnus clustered at levels of sequence homology of 84 to 93%. This duster was not included in the Peptococcus niger group or the Peptostreptococcus anaerobius group. Thus, these members of the genus Peptostreptococcus should be separated from the other members of the genus and also from members of the family Peptococcaceae. The sequence of Peptostreptococcus productus ATCC 27340T was different from the sequences of Peptostreptococcus anaerobius and Peptococcus niger. The sequence of Streptococcus hansenii ATCC 27752T, a strictly anaerobic strain, was different from the sequences of other streptococci; this strain clustered with Peptostreptococcus productus, coprococci, and ruminococci. Several phenotypic characteristics of Streptococcus hansenii ATCC 27752T were similar to characteristics of ruminococci. These organisms require fermentable carbohydrates and do not produce butyric acid from glucose. Thus, we propose that Peptostreptococcus productus and Streptococcus hansenii should be transferred to the genus Ruminococcus.