Description of Mogibacterium pumilum gen. nov., sp nov and Mogibacterium vescum gen. nov., sp nov., and reclassification of Eubacterium timidum (Holdeman et al. 1980) as Mogibacterium timidum gen. nov., comb. nov.

A new genus, Mogibacterium, is proposed for anaerobic, non-spore-forming, G ram-positive, rod-shaped bacteria which have been isolated from the periodo ntal pockets of adult human patients with periodontal disease and infected root canals. The novel isolates, strains D2-18(T), BA11a-f and D5-2(T), wer e inert in most of the conventional biochemical tests and phenotypically re semble asaccharolytic Eubacterium species. The protein profiles of whole ce lls on SDS-PAGE gels and Western immunoblotting reaction analysis distingui shed these organisms from type strains belonging to the previously describe d Eubacterium species. The G+C content of the DNA is 45-46 mol% for Mogibac terium pumilum and 46 mol% for Mogibacterium vescum. The levels of DNA-DNA relatedness of these new species to other Eubacterium species, including Eu bacterium limosum, Eubacterium brachy, Eubacterium lentum, Eubacterium noda tum, Eubacterium spahenum, and the more recently proposed Eubacterium minut um and Eubacterium exiguum (reclassified as Slackia exigua), are less than 2%. The DNA-DNA hybridization value between M. pumilum and M. vescum was 30 %. Eubacterium timidum exhibited DNA homologies with Mogibacterium species which were low (17 and 18%) but clearly higher than with all the other Euba cterium species. phylogenetic analysis based on 16S rRNA gene sequences rev ealed that the closest phylogenetic neighbour of Mogibacterium species was E. timidum, and that these three species represent a novel lineage distinct from the previously described genera of Gram-positive, rod-shaped bacteria . On the basis of phenotypic characteristics and 16S rRNA gene sequence com parisons, it is also proposed that E. timidum is transferred to the genus M ogibacterium gen. nov. as Mogibacterium timidum gen. nov., comb. nov. (type strain ATCC 33093(T)).