Transfer of Bacteroides succinogenes (Hungate) to Fibrobacter gen. nov. as Fibrobacter succinogenes comb. nov. and Description of Fibrobacter intestinalis sp. nov.

Abstract

A comparison of 16S ribosomal ribonucleic acid sequences showed that strains classified as Bacteroides succinogenes are not closely related to other species of Bacteroides, including the type species, Bacteroides fragilis. Flavobacterium heparinum, for example, is more closely related to B. fragilis than B. succinogenes is. Therefore, we propose that B. succinogenes strains be renamed as members of a new genus, Fibrobacter. An analysis of 16S ribosomal ribonucleic acid sequence data revealed that there are two species within this new genus. Isolates from rumina are placed in Fibrobacter succinogenes; the type strain is strain S85 (= ATCC 19169). Isolates from ceca of nonruminant animals are placed in Fibrobacter intestinalis; the type strain is strain NR9 (= ATCC 43854). Members of Fibrobacter succinogenes can be differentiated from Fibrobacter intestinalis by their requirement for biotin; the site of isolation may not be diagnostic. Fibrobacter succinogenes consists of two subspecies; the cells of Fibrobacter succinogenes subsp. succinogenes strains are broad rods that are often pleomorphic and coccoid (type strain, S85), whereas cells of Fibrobacter succinogenes subsp. elongata are slender rods (type strain, HM2 [= ATCC 43856]).