Fusibacter Fontis Sp Nov., A Sulfur-Reducing, Anaerobic Bacterium Isolated From A Mesothermic Tunisian Spring

Strain KhalAKB1(T), a mesophilic, anaerobic, rod-shaped bacterium, was isolated from water collected from a mesothermic Tunisian spring. Cells were Gram-staining-Positive rods, occurring singly or in pairs and motile by one lateral flagellum. Strain KhalAKB1(T) grew at 15-45 degrees C (optimum 30 degrees C), at pH 5.5-8.5 (optimum pH 7.0) and in the presence of 0-35 g NaCl l(-1) (optimum 1 g NaCl l(-1)). It fermented yeast extract and a wide range of carbohydrates including cellobiose, D-glucose, D-ribose, sucrose, D-xylose, maltose, D-galactose and starch as electron donors. Acetate, ethanol, CO2 and H-2 were end products of glucose metabolism. It reduced elemental sulfur, but not sulfate, thiosulfate or sulfite, into sulfide. The DNA G+C content was 37.6 mol%. The predominant cellular fatty acids were C-14 : 0 and C-16 : 0. Phylogenetic analysis of the 16S rRNA gene sequence suggested Fusibacter bizertensis as the closest relative of this isolate (identity of 97.2 % to the type strain). Based on phenotypic, phylogenetic and genotypic taxonomic characteristics, strain KhalAKB1(T) is proposed to be assigned to a novel species within the genus Fusibacter, order Clostridiales, Fusibacter fontis sp. nov. The type strain is KhalAKB1(T) (=DSM 28450(T)=JCM 19912(T)).