A novel thermophilic, anaerobic, Gram-stain-positive, terminal-spore-forming bacterium was isolated from an upflow anaerobic filter treating abattoir wastewaters in Tunisia. This strain, designated LIND6LT2(T), grew at 40-60 °C (optimum 50-55 °C) and at pH 6.0-8.5 (optimum pH 7.0-7.5). It did not require NaCl for growth, but tolerated it up to 2%. Sulfate, thiosulfate, elemental sulfur, sulfite, nitrate and nitrite were not used as electron acceptors. Growth of LIND6LT2(T) was inhibited by sulfite (2 mM). Strain LIND6LT2(T) used cellobiose, glucose, mannose, maltose, mannitol, sucrose and xylose as electron donors. The main fermentation products from glucose metabolism were acetate, formate, butyrate and isobutyrate. The predominant cellular fatty acids were C(16:0) (68.4%) and C(14:0) (8.3%). The G+C content of the genomic DNA was 35.2 mol%. On the basis of its phylogenetic and physiological properties, a new genus and species, Defluviitalea saccharophila gen. nov., sp. nov., are proposed to accommodate strain LIND6LT2(T), placed in Defluviitaleaceae fam. nov. within the phylum Firmicutes, class Clostridia, order Clostridiales. Strain LIND6LT2(T) (=DSM 22681(T) =JCM 16312(T)) is the type strain of Defluviitalea saccharophila, which itself is the type species of Defluviitalea.