Bifidobacterium stercoris sp. nov., isolated from human faeces.

Strain Eg1(T), an anaerobic, Gram-stain-positive, non-motile and non-spore-forming bacterium, was isolated from human faeces. The optimal temperature for growth was 37 °C and tests for oxidase and catalase activities gave negative results. Fructose-6-phosphate phosphoketolase activity was detected. Acid was produced during fermentation of several substrates, including glucose. The end products of glucose fermentation were acetic acid and lactic acid, which were produced in a molar ratio of 1.76 : 1 (approximately 3 : 2). The G+C content was 57.8 mol%. Comparative analysis of 16S rRNA gene sequences showed that strain Eg1(T) was closely related to Bifidobacterium adolescentis YIT 4011(T) (98.36 % 16S rRNA gene sequence similarity) and Bifidobacterium ruminantium JCM 8222(T) (97.93 %) and analysis of hsp60 sequences showed that strain Eg1(T) was closely related to B. adolescentis JCM 1275(T) (99.35 % hsp60 sequence similarity) and B. ruminantium JCM 8222(T) (92.13 %). However, despite these degrees of similarity being high enough for strain Eg1(T) to be included at the same species level as B. adolescentis and B. ruminantium (96.5-100 % for the genus Bifidobacterium), the isolate could be distinguished from B. adolescentis KCTC 3216(T) and B. ruminantium KCTC 3425(T) by low levels of DNA-DNA relatedness (41 and 17 %, respectively). Based on phenotypic, genotypic and phylogenetic analyses, we propose that strain Eg1(T) is classified in a novel species, Bifidobacterium stercoris sp. nov. The type strain is Eg1(T) (=KCTC 5756(T) =JCM 15918(T)).