Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Wed, 07 Nov 2018 18:21:47 Note Phylogenetic analysis of some Sporomusa sub-branch members isolated from human clinical specimens: description of Megasphaera micronuciformis sp. nov. He ´ le ` ne Marchandin, 1 Estelle Jumas-Bilak, 2 Bernard Gay, 1 Corinne Teyssier, 2 He ´ le ` ne Jean-Pierre, 1 Miche ` le Sime ´ on de Buochberg, 2 Christian Carrie `re 1 and Jean-Philippe Carlier 3 Correspondence He ´le ` ne Marchandin h-marchandin@chu-montpellier.fr 1 Laboratoire de Bacte ´ riologie, Ho ˆ pital Arnaud de Villeneuve, 371 Avenue du doyen Gaston Giraud, F-34295 Montpellier Cedex 5, France 2 Laboratoire de Bacte ´ riologie, Faculte ´ de Pharmacie, F-34060 Montpellier Cedex 2, France 3 Centre National de Re ´fe ´ rence des Bacte ´ ries Anae ´ robies, Institut Pasteur, 25 rue du Dr Roux, F-75724 Paris Cedex 15, France Two unknown, Gram-negative, catalase-negative and strictly anaerobic cocci were isolated from two independent human samples (strains AIP 49.01 and AIP 412.00 T ). Comparative 16S rRNA gene sequencing demonstrated that these two organisms displayed 99?8 % sequence identity and that they are members of the Sporomusa sub-branch of the low-G+C Gram-positive bacteria. The most closely related 16S rDNA sequences were from Megasphaera sp. oral clone BU057 (99?8 %) and from isolates of Megasphaera cerevisiae and Megasphaera elsdenii (94?5 and 93?8 %, respectively). Phylogenetic analysis based on 16S rDNA sequences showed that these two strains were most closely related to M. elsdenii and belonged to the Megasphaera genus. Differences from previously described Megasphaera species in terms of size, biochemical tests (particularly the analysis of metabolic end products), gas production and DNA G+C content indicated that the two strains studied represent a novel species of anaerobic Gram-negative cocci. The name Megasphaera micronuciformis sp. nov. is proposed for these two isolates. It is also proposed that the uncultured organism previously deposited as Megasphaera sp. oral clone BU057 should be named ‘Candidatus Megasphaera micronuciformis’. The type strain of Megasphaera micronuciformis is AIP 412.00 T (=CIP 107280 T =CCUG 45952 T ). In phenetic taxonomy, all the strictly anaerobic Gram- negative cocci were originally classed as a single family, the Veillonellaceae (Rogosa, 1971, 1984). Three genera were accepted into this family: Veillonella, Acidaminococcus and Megasphaera. Recently, Anaeroglobus geminatus gen. nov., sp. nov. was described (Carlier et al., 2002). This genus, consisting of strictly anaerobic Gram-negative cocci isolated from human samples, was included in the family Veillonellaceae. Phylogenetic taxonomy showed that the four previous genera, despite the negative Gram stain, belonged to the Sporomusa sub-branch of the Firmicutes (Carlier et al., 2002). More recently, in Bergey’s Manual of Systematic Bacteriology (Garrity & Holt, 2001) all mem- bers of the Sporomusa sub-branch were grouped in the family Acidaminococcaceae. As a consequence, the family Veillonellaceae was excluded from this new classification. In recent studies, culture-independent methods based on 16S rDNA cloning and sequence analysis have been used to determine the bacterial diversity of oral flora (Paster et al., 2001; Rolph et al., 2001). Consequently, an increasing number of sequences corresponding to uncultivated bac- teria belonging to the Sporomusa sub-branch have been deposited in databases. These results suggest that many members of this phylogenetic branch remain unknown. Furthermore, in a routine medical microbiology exercise, we isolated five unidentified strains affiliated to the Sporomusa sub-branch on the basis of 16S rDNA sequences. Although three of them are not completely characterized, they seem Abbreviation: EM, electron microscopy. Published online ahead of print on 23 August 2002 as DOI 10.1099/ ijs.0.02378-0. The GenBank/EMBL/DDBJ accession numbers for the 16S rDNA sequences of Megasphaera micronuciformis AIP 49.01 and AIP 412.00 T are AF473833 and AF473834, respectively. A full version of the phylogenetic dendrogram is available as supplementary data in IJSEM Online (http://ijs.sgmjournals.org). 02378 G 2003 IUMS Printed in Great Britain 547 International Journal of Systematic and Evolutionary Microbiology (2003), 53, 547–553 DOI 10.1099/ijs.0.02378-0