Clostridium hydroxybenzoicum JW/Z-1T (= ATCC 51151 = DSM 7310)) (T = type strain), isolated from freshwater pond sediment, is a nonmotile, gram type-positive, spore-forming, amino acid-utilizing, anaerobic rod. This bacterium produces two inducible enzymes that catalyze the decarboxylation of para-hydroxybenzoates. The phenols produced are not utilized. C. hydroxybenzoicum requires yeast extract for growth. Sugars are not utilized. Sodium ions and acetic acid stimulate growth. The optimal temperature and optimal pH for growth are 33 to 34 degrees C and 7.2 to 8.2, respectively. The DNA base composition of the type strain is 35.5 mol% guanine plus cytosine, whereas the DNA base compositions of the type strains of Clostridium sticklandii and Clostridium aminovalericum are 33 and 33.5 mol% guanine plus cytosine, respectively, as determined by a chemical method. 16S rRNA sequence analysis groups strain JW/Z-1T most closely with Clostridium purinolyticum and Clostridium acidurici (10.6 and 11 inferred changes per 100 bases, respectively). However, C. hydroxybenzoicum does not utilize uric acid, hypoxanthine, xanthine, adenine, or guanine. The cell wall type is A1 alpha (L-Lys direct).