Reclassification of Clostridium hydroxybenzoicum as Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., and description of Sedimentibacter saalensis sp nov.

Strain ZF2(T), isolated from freshwater sediment, is a motile, rod-shaped, Gram-positive, endospore-forming, amino acid- and pyruvate-utilizing, anaerobic bacterium. It requires yeast extract for growth. Carbohydrates are not utilized. The optimal temperature and pH for growth are 37 degreesC and 6.8-7.3, respectively. The G+C content of the DNA is 34.0 mol%. A 16S rDNA sequence analysis of strain ZF2(T) revealed that the highest similarity (94.4%) was shared with Clostridium hydroxybenzoicum JW/Z-1(T). Strain ZF2(T), however, was not able to carboxylate phenol or to decarboxylate 4-hydroxybenzoate, which are characteristic properties of strain JW/Z-1(T). The degree of 16S rDNA relatedness, together with the physiological and chemotaxonomic properties, suggest that strain ZF2(T) represents a novel species that is clearly distinct from Clostridium hydroxybenzoicum JW/Z-1(T). In a phylogenetic dendrogram, both strains form a separate cluster that is peripherally associated with the Peptostreptococcus group (cluster XIII) of the clostridia and the lineage of Helcococcus kunzii. Strains ZF2(T) and JW/Z-1(T) show a somewhat deeper branching from the cluster XII clostridia Clostridium purinolyticum and Clostridium acidiurici. The latter strains possessed the closest 16S rDNA similarity (between 88.4 and 90.7%), but were clearly separated by phenotypic markers. Therefore, a new genus, Sedimentibacter gen. nov., is described, comprising Sedimentibacter hydroxybenzoicus gen. nov., comb. nov., as the type species of the genus, with JW/Z-1(T) (= ATCC 51151(T) = DSM 731(T)) as the type strain, and the novel species Sedimentibacter saalensis sp. nov., with strain ZF2(T) (= DSM 13558(T) = ATCC BAA-283(T)) as the type strain.