Deoxyribonucleic Acid Relatedness among Strains of the Species Butyrivibrio fibrisolvens

Abstract

A total of 39 strains assigned to the strictly anaerobic species Butyrivibrio fibrisolvens were examined for deoxyribonucleic acid (DNA) relatedness. The guanine-plus-cytosine (G+C) base contents determined from the buoyant densities of chromosomal DNAs of 27 strains were 39.0 to 42.0 mol%. Another nine strains had G+C contents of 42.0 to 45.0 mol%, and three other strains had higher G+C contents (46.4 to 49.2 mol%). Genetic relationships among the strains were determined by DNA hybridizations, using both spectrophotometric and membrane filter techniques. The relationships derived by both methods are compared. The G+C content and hybridization results indicate that the strains comprise a genetically heterogeneous group, representing a number of distinct species. Strain D1, the type strain of B. fibrisolvens, was not closely related to any of the other 38 strains. Five groups of related bacteria, encompassing 20 Butyrivibrio strains, were identified as forming five separate species. The largest group identified by DNA relatedness as belonging to the same species contained only six strains. The other 19 strains were not closely related to any other strain.