Proposal of Roseburia faecis sp. nov., Roseburia hominis sp. nov. and Roseburia inulinivorans sp. nov., based on isolates from human faeces

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Abstract
Seven recently cultured bacterial isolates, although similar in their 16S rRNA gene sequences toRoseburia intestinalisL1-82T(DSM 14610T), were not sufficiently related for inclusion within existing species, forming three separate clusters in a 16S rRNA gene phylogenetic tree. The isolates, which were obtained from human stools, were Gram-variable or Gram-negative, strictly anaerobic, slightly curved rods; cells from all strains measured approximately 0.5×1.5–5.0 μm and were motile. Two strains belonging to one cluster (A2-181 and A2-183T) were the only strains that were able to grow on glycerol and that failed to grow on any of the complex substrates tested (inulin, xylan and amylopectin). Strains belonging to a second cluster (represented by M6/1 and M72/1T) differed from the other isolates in their ability to grow on sorbitol. Isolates belonging to a third cluster (L1-83 and A2-194T) were the only strains that failed to grow on xylose and that gave good growth on inulin (strains M6/1 and M72/1Tgave weak growth). All strains were net acetate utilizers. The DNA G+C contents of representativeRoseburiastrains A2-183T, A2-194T, M72/1TandR. intestinalisL1-82Twere 47.4, 41.4, 42.0 and 42.6 mol%, respectively. Based on 16S rRNA gene sequence similarity, three novelRoseburiaspecies are proposed, with the namesRoseburia hominissp. nov. (type strain A2-183T=DSM 16839T=NCIMB 14029T),Roseburia inulinivoranssp. nov. (type strain A2-194T=DSM 16841T=NCIMB 14030T) andRoseburia faecissp. nov. (type strain M72/1T=DSM 16840T=NCIMB 14031T).