RESUMO
Phenotypic and phylogenetic studies were performed on 15 isolates of an unidentified Gram-positive, anaerobic, non-sporulating coccobacillus-shaped bacterium isolated from human faeces. The novel organisms were catalase-negative, indole-negative and produced acetate and succinate as end products of metabolism. Comparative 16S rRNA gene sequencing demonstrated that the 15 isolates were highly related to each other and formed a hitherto unknown subline within the clostridial rRNA cluster XIVa. The novel isolates formed a robust phylogenetic group with a number of organisms which included Clostridium coccoides, Ruminococcus luti, Ruminococcus obeum and a number of other misclassified ruminococci. On the basis of these studies, a novel genus, Blautia gen. nov., is proposed. It is suggested that Clostridium coccoides, Ruminococcus hansenii, Ruminococcus hydrogenotrophicus, Ruminococcus luti, Ruminococcus productus, and Ruminococcus schinkii are transferred to this genus as Blautia coccoides gen. nov., comb. nov., Blautia hansenii comb. nov., Blautia hydrogenotrophica comb. nov., Blautia luti comb. nov., Blautia producta comb. nov. and Blautia schinkii comb. nov. One of the new isolates, the hitherto unknown coccus-shaped bacterial strain WAL 14507T (=ATCC BAA-1564T=DSM 19850T) is proposed as representing the type strain of a novel species, Blautia wexlerae sp. nov.
Assuntos
Clostridium/classificação , Fezes/microbiologia , Bactérias Gram-Positivas/classificação , Ruminococcus/classificação , Acetatos/metabolismo , Técnicas de Tipagem Bacteriana , Criança , Pré-Escolar , Clostridium/genética , Clostridium/fisiologia , DNA Bacteriano/análise , DNA Ribossômico/análise , Genes de RNAr , Bactérias Gram-Positivas/genética , Bactérias Gram-Positivas/isolamento & purificação , Bactérias Gram-Positivas/fisiologia , Humanos , Dados de Sequência Molecular , Fenótipo , Filogenia , RNA Ribossômico 16S/genética , Ruminococcus/genética , Ruminococcus/fisiologia , Análise de Sequência de DNA , Especificidade da Espécie , Succinatos/metabolismoRESUMO
The 16S rRNA gene sequence of the type strain of Ruminococcus flavefaciens, the type species of the genus Ruminococcus, was determined by PCR direct sequencing. A comparative sequence analysis showed that R. flavefaciens is phylogenetically related to a small cluster (cluster IV of Collins et al. [M. D. Collins, P. A. Lawson, A. Willems, J. J. Cordoba, J. Fernandez-Garayzabal, P. Garcia, J. Cai, H. Hippe, and J. A. E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994]) of organisms which includes several Clostridium and Eubacterium species. R. flavefaciens was found to be phylogenetically only remotely related to Ruminococcus gnavus, Ruminococcus torques, Peptostreptococcus productus, and Streptococcus hansenii. These findings demonstrate that the genus Ruminococcus is not a monophyletic group, and the proposed transfer of P. productus and S. hansenii to this genus (T. Ezaki, N. Li, Y. Hashimoto, H. Miura, and H. Yamamoto, Int. J. Syst. Bacteriol. 44:130-136, 1994) is not supported.