Augmentation of dietary glucosylceramide hydrolysis by the novel bacterium Glucerabacter canisensis NATH-2371T.

The purpose of this study was to evaluate the effects of intragastrical administration of Glucerabacter canisensis NATH-2371T on glucosylceramide (GluCer) digestion in mice. Although G. canisensis was unable to utilize starch and cellulose, coculture of G. canisensis with mouse fecal bacteria greatly increased GluCer hydrolysis in polysaccharide medium, indicating that G. canisensis grew in competition with other intestinal bacteria. Although most of the administered G. canisensis cells were detected in feces, some cells were present in the colorectum contents, which had GluCer-hydrolyzing activity. These results indicate that G. canisensis can viably transit through the mouse gut. Administration of G. canisensis to mice fed diets supplemented with GluCer or GluCer-containing foods significantly enhanced GluCer hydrolysis. Since G. canisensis did not show acute toxicity, it may be useful as a probiotic to augment GluCer hydrolysis in the large intestine. Abbreviations: GluCer: glucosylceramide; KPi: potassium phosphate buffer; C-M: chloroform-methanol.

Glucerabacter canisensis gen. nov., sp. nov., isolated from dog feces and its effect on the hydrolysis of plant glucosylceramide in the intestine of dogs.

A Gram-positive, obligately anaerobic, oval-rod shaped, non-spore-forming, and non-pigmented bacterium, designated strain NATH-2371T (= JCM31739T = DSM105698T), was isolated from dog feces. Comparative 16S rRNA gene sequence analysis revealed that strain NATH-2371T belongs to Clostridium cluster XIVa, and the closest strains were Coprococcus comes ATCC 27758T (94.8% 16S rRNA gene sequence similarity) and Clostridium nexile DSM 1787T (94.0%). Strain NATH-2371T produced acetate, formate, and ethanol from glucose. Predominant cellular fatty acids are C16:0 and C16:0 DMA. On the basis of the phenotypic and genotypic differences, strain NATH-2371T represents a novel species in a new genus of the family Lachnospiraceae, for which the name Glucerabacter canisensis gen. nov., sp. nov., is proposed. This strain was found to efficiently hydrolyze plant glucosylceramide (GluCer). The abundance of strain NATH-2371T in dog feces was higher in young dogs than in old dogs. Incubation of dog fecal bacteria showed that GluCer-hydrolyzing activity decreased with the age of dogs. The cell number of strain NATH-2371T in dog feces appeared to be correlated with GluCer hydrolysis. Thus, this bacterium is likely to play a major role in GluCer hydrolysis in the dog intestine.