Résumé
Three strains of a hitherto unknown, Gram-negative staining, tiny, anaerobic coccus were collected from human clinical samples originating from skin and soft tissues. The three isolates displayed at least 99.9% identity in 16S rRNA gene sequences and more than 99.8% identity in dnaK gene sequences. The isolates were affiliated to the family Veillonellaceae, the coccobacillus Dialister micraerophilus being the most closely related species but with no more than 91.1% in 16S rRNA gene sequences. Phylogeny based on 16S rRNA gene confirmed that the three strains represent a novel and robust lineage within the current family Veillonellaceae. Similar genomic structure was demonstrated for the three isolates by pulsed-field gel electrophoresis-based analysis. Morphology and metabolic end products, as well as genotypic and phylogenetic data supported the proposal of the novel genus Negativicoccus gen. nov. with the novel species Negativicoccus succinicivorans sp. nov. (type strain ADV 07/08/06-B-1388T (= AIP 149.07T = CIP 109806T = DSM 21255 T = CCUG 56017T) as type species. Phylogenetic analyses based on 16S rRNA gene sequences of members of the phylum Firmicutes and other phyla indicated that the family Veillonellaceae formed a robust lineage clearly separated from those of the classes 'Bacilli', 'Clostridia', Thermolithobacteria and 'Erysipelotrichi' in the phylum Firmicutes. Therefore, we proposed that this family is a class-level taxon in the phylum Firmicutes, for which the name Negativicutes classis nov. is proposed, based on the Gram-negative type of cell wall of its members, with type order Selenomonadales ord. nov. In this order, a novel family, Acidaminococcacae fam. nov., is proposed and description of the family Veillonellaceae is emended.