TAXONOMIC RELATEDNESS OF BUTYRIVIBRIO, LACHNOSPIRA, ROSEBURIA, AND EUBACTERIUM SPECIES AS DETERMINED BY DNA HYBRIDIZATION AND EXTRACELLULAR-POLYSACCHARIDE ANALYSIS

DNA hybridization and extracellular-polysaccharide (EPS) analyses were performed for 19 strains of Butyrivibrio fibrisolvens and six strains of Butyrivibrio crossotus, Lachnospira maltipara, Roseburia cecicola, and Eubacterium rectale. Both methods showed that these strains constitute a heterogeneous group of bacteria, and both methods sorted the strains into related groups. As determined by DNA analysis, 20 strains formed five separate groups of closely related bacteria. Nine of these strains were closely related to two previously established groups of B. fibrisolvens. These two groups, group 1 and group 3, contain 11 and 8 strains, respectively, and could represent new species. The type strain of B. crossotus, an isolate from human feces, was closely related genetically to five of the strains presently identified as B. fibrisolvens, which were isolated from rumina of bison. The groups formed by EPS analysis were similar to those formed by DNA analysis. Our data suggest that for some groups of microorganisms EPS analysis may be a useful adjunct to DNA analysis to clarify complex taxonomic relationships.