Bifidobacterium stercoris sp. nov., isolated from human faeces

Abstract

Strain Eg1T, 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 Eg1T was closely related to Bifidobacterium adolescentis YIT 4011T (98.36 % 16S rRNA gene sequence similarity) and Bifidobacterium ruminantium JCM 8222T (97.93 %) and analysis of hsp60 sequences showed that strain Eg1T was closely related to B. adolescentis JCM 1275T (99.35 % hsp60 sequence similarity) and B. ruminantium JCM 8222T (92.13 %). However, despite these degrees of similarity being high enough for strain Eg1T 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 3216T and B. ruminantium KCTC 3425T by low levels of DNA–DNA relatedness (41 and 17 %, respectively). Based on phenotypic, genotypic and phylogenetic analyses, we propose that strain Eg1T is classified in a novel species, Bifidobacterium stercoris sp. nov. The type strain is Eg1T (=KCTC 5756T =JCM 15918T).