No abstract

A strictly anaerobic, mesophilic, cellulolytic bacterial strain, designated CDT-1 T , was isolated from rice-straw residue from a methanogenic reactor treating waste from cattle farms. The isolation was performed using enrichment culture with filter paper as a substrate. Cells stained Gram-negative, but reacted Gram-positively in the KOH test. Cells were slightly curved rods and were motile by means of peritrichous flagella. The strain produced yellow pigment when grown on filter-paper fragments. Although spore formation was not confirmed microscopically, thermotolerant cells were produced when the strain was grown on filter paper. The optimum temperature for growth was 33 6C and the optimum pH was 7.4. Oxidase, catalase and nitrate-reducing activities were absent. The strain utilized xylose, fructose, glucose, cellobiose, xylooligosaccharide, cellulose (filter-paper fragments and ball-milled filter paper) and xylan. The major fermentation products were acetate, ethanol, H 2 and CO 2 . The major cellular fatty acids were iso-C 15 : 0 , iso-C 14 : 0 and C 16 : 0 DMA. The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The genomic DNA G+C content was 40.7 mol%. On the basis of 16S rRNA gene sequence similarities, strain CDT-1 T could be placed in cluster III of the genus Clostridium, being closely related to type strains of Clostridium hungatei (96.6 % sequence similarity), Clostridium termitidis (96.2 %) and Clostridium papyrosolvens (96.1 %). On the basis of the cellular, physiological and phylogenetic differences between CDT-1 T and its close relatives, this strain represents a novel species of the genus Clostridium, for which the name Clostridium sufflavum sp. nov. is proposed. The type strain is CDT-1 T (5JCM 14807 T 5DSM 19573 T ).