Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/13/2006
Publication Date: 10/20/2006
Citation: Duncan, S.H., Aminov, R.I., Scott, K.P., Louis, P., Stanton, T.B., Flint, H.J. 2006. Proposal of Roseburia faecis sp. nov., Roseburia hominis sp. nov. and Roseburia inulinivorans sp. nov., based on isolates from human faeces. International Journal of Systematic and Evolutionary Microbiology. 56(10):2437-41. Interpretive Summary: Roseburia is a genus of bacteria commonly found in the intestinal tracts of mammals, including humans. One of the interesting and potentially useful features of Roseburia species is that these bacteria make butyrate, a volatile fatty acid considered to be benefical for intestinal tissues. In this study several previously unknown species of Roseburia were isolated from the feces of healthy humans. These new species were characterized and were named. Additionally, a fluorescent molecular probe was used to detect and directly count Roseburia cells in human feces. The Roseburia were found to represent 10%, a high percentage of the total bacteria. Thus Roseburia species contribute significantly, in terms of population numbers and desirable butyrate production, to the intestinal microbial ecosystem.
Technical Abstract: Phylogenetic analysis of bacterial 16S rRNA sequences amplified from the human gut reveals a group within the Clostridial cluster XIVa that includes the cultivated bacterial species Roseburia intestinalis and Eubacterium rectale. 16S rRNA sequences from 20 recent cultivated isolates of human butyrate-producing bacteria are shown here to fall within five of the eight OTUs identified by amplified sequences from human faeces. In addition to the two known species, R. cecicola and R. intestinalis, three new species, R. hominis, R. inulovorans, and R. faecalis are proposed on the basis of phenotypic and genotypic criteria. A further expansion of the genus Roseburia is also proposed here to include the species Roseburia (formerly Eubacterium) rectale (comb. nov.) based on the characteristics of newly isolated strains. Strains belonging to the Roseburia genus are butyrate-producing, anaerobic, rod shaped, motile, Gram-negative or Gram-variable bacteria. A new 16S rRNA targetted oligonucleotide probe Rrec584 was designed that recognises all Roseburia species except R. inulovorans. In addition, a previous broader probe Rint623 was made more suitable for fluorescent in situ hybridisation (FISH) detection by designing a helper oligonucleotide. These two probes recognised similar numbers of bacteria in faeces from 10 healthy volunteers, corresponding to approximately 10% of those detected by the eubacterial probe Eub338.