Hydrogenoanaerobacterium saccharovorans gen. nov., sp nov., isolated from H2-producing UASB granules

Two strictly anaerobic bacterial strains, designated SW512 (T) and W72, were isolated from a laboratory-scale H-2-producing up-flow anaerobic sludge blanket (UASB) reactor. Cells were Gram-stain-negative, non-motile and 0.3-0.4x2.0-14.5 mu m; they did not form spores. Both strains grew at 24-45 degrees C (no growth at <= 22 degrees C or >= 46 degrees C), with optimum growth at 37 degrees C. The pH range for growth was 4.5-9.0 (no growth at pH <= 4.2 or pH >= 9.3), with optimum growth at pH 6,5-7.0. Several kinds of mono-, di- and oligosaccharides supported growth. The main end products of glucose fermentation were ethanol, acetate, hydrogen and carbon dioxide (according to the equation 1 mol glucose -> 1. 1 mol acetate + 0.6 mol ethanol + 2.6 mol H-2 + 1.6 mol CO2)The DNA G+C contents of strains SW512(T) and W72 were 41.9 +/- 10.5 and 42.8 +/- 0.4 mol% (T-m method), respectively. Phylogenetic analysis based on 16S rRNA gene sequence similarities indicated that the two strains represent a new phyletic sublineage, within the family 'Ruminococcaceae', with < 9 1.3% 16S rRNA gene sequence similarity to recognized species. On the basis of the polyphasic evidence in this study, it is proposed that the two strains represent a novel species in a new genus, for which the name Hhydrogenoanaerobacterium saccharovorans gen. nov., sp. nov. is proposed; the type strain of the type species is SW512(T) (=AS 1.5070(T)-JCM 14861(T)).