Characterization of a new xylanolytic bacterium, Clostridium xylanovorans sp nov.

A new xylanolytic bacterium designated strain HESP1(T) (T = type strain) was isolated from a methanogenic digester. Strain HESP1T was a motile, rod shaped, spore-forming bacterium, which possessed a Gram-positive type cell wall. Glucose, fructose, lactose, trehalose, maltose, raffinose, sucrose, xylan, mannitol, cellobiose, galactose, mannose, melibiose, ribose were fermented to prc,duce, acetate, butyrate. H-2, CO2, formate, isobutyrate, and ethanol. Fumarate was fermented to acetate. Glycerol and methanol were also utilized. Sulfate, thiosulfate, nitrate, sulfur and fumarate were not used as electron accepters. Strain HESP1(T) had a G+C content of 40 mol% and grew optimally at 37 degrees C and pH 7 on a fructose containing medium. Phylogenetically, strain HESP1(T) was most related to Clostridium aminovalericum (similarity of 94%) than to C. populeti, C. herbivorans and Eubacterium xylanophilum (average similarity of 92%), all members of subcluster XIVa of the low G+C containing Gram-positive branch. However, strain HESP1(T) shared little phenotypic and genotypic traits with C. aminovalericum and on the basis of this and phylogenetic evidence, we propose to tentatively designate strain HESP1T as a new species of the genus Clostridium, Clostridium xylanvorans sp. nov. The type strain is HESP1(T) (= DSM 12503).