Clostridium phytofermentans sp nov., a cellulolytic mesophile from forest soil

An obligately anaerobic, mesophilic, cellulolytic bacterium, strain ISDg(T), was isolated from forest soil. Cells of this isolate stained Gram-negative, despite possessing a Gram-positive cell-wall ultrastructure, and were motile, straight rods that formed spherical terminal spores that swelled the sporangium. Cellulose, pectin, polygalacturonic acid, starch, xylan, arabinose, cellobiose, fructose, galactose, gentiobiose, glucose, lactose, maltose, mannose, ribose and xylose supported growth. The major end products of fermentation were ethanol, acetate, CO2 and H-2; formate and lactate were minor products. The optimum temperature for growth was 35-37 degreesC. Phylogenetic analyses based on 16S rRNA sequence comparisons showed that strain ISDg(T) was related to a group of anaerobes that included Clostridium herbivorans, Clostridium polysaccharolyticum and Clostridium populeti. The G+C content of this strain was 35.9 mol%. On the basis of numerous genotypic and phenotypic differences between strain ISDg(T) and its close relatives, strain ISDg(T) is proposed as a novel species in the genus Clostridium, for which the name Clostridium phytofermentans sp. nov. is proposed. The type strain is ISDg(T) (= ATCC 700394(T)).