Bacteroides cellulosilyticus sp. nov., a cellulolytic bacterium from the human gut microbial community

A strictly anaerobic cellulolytic bacterium, strain CRE21T, was isolated from a human faecal sample. Cells were Gram-negative non-motile rods that were about 1.7 μm in length and 0.9 μm in width. Strain CRE21T degraded different types of cellulose and was able to grow on a variety of carbohydrates. Cellulose and sugars were mainly converted to acetate, propionate and succinate. The G+C content of the DNA was 41.1 mol%. 16S rRNA gene sequence analysis revealed that the isolate belonged to the genus Bacteroides with highest sequence similarity to the type strain of Bacteroides intestinalis (98 %). DNA–DNA hybridization results revealed that strain CRE21T was distinct from B. intestinalis (40 % DNA–DNA relatedness). Strain CRE21T also showed several characteristics distinct from B. intestinalis. In particular, it exhibited different capacity to degrade polysaccharides such as cellulose. On the basis of phylogenetic analysis and the morphological, physiological and biochemical data presented in this study, strain CRE21T can be readily differentiated from recognized species of the genus Bacteroides. The name Bacteroides cellulosilyticus sp. nov. is proposed to accommodate this organism. The type strain is CRE21T (=DSM 14838T=CCUG 44979T).