Isolation of a novel bacterium, Blautia glucerasei sp. nov., hydrolyzing plant glucosylceramide to ceramide.

A bacterial strain that is capable of hydrolyzing plant glucosylceramide (GluCer) was newly isolated from dog feces. The novel strain, designated as strain HFTH-1(T), hydrolyzed plant GluCer with a variety of chemical structures, but did not hydrolyze glucosylsphingosine, lactosylceramide, or monosialoganglioside GM(3), indicating that strain HFTH-1(T) produces GluCer-specific glucosylceramidase. Strain HFTH-1(T) was Gram-positive, anaerobic, oval-spore-forming, rod-shaped, lecithinase-negative, and lipase-negative. It fermented a wide variety of carbohydrates and produced mainly acetate, formate, and lactate from glucose. The G + C content of its DNA was 40.7 mol%. The phylogenetic analysis of 16S rRNA sequence revealed that strain HFTH-1(T) is placed in the clostridial rRNA cluster XIVa, with Ruminococcus obeum as the nearest relative. Pairwise comparison revealed approximately 5.0% sequence divergence between strain HFTH-1(T) and the type strain of R. obeum. On the basis of its phenotypic characteristics and phylogenetic divergence, it is proposed that the hitherto unknown rod-shaped bacterial strain HFTH-1(T) (= DSM 22028(T) = NBRC 104932(T)) should be placed in the genus Blautia as a novel species, Blautia glucerasei sp. nov, the only currently known isolate of the species.