ANAEROBACULUM THERMOTERRENUM GEN-NOV, SP-NOV, A NOVEL, THERMOPHILIC BACTERIUM WHICH FERMENTS CITRATE

A thermophilic anaerobic bacterium designated strain RWcit2(T) (T = ty pe strain) was isolated from the production water of a petroleum reser voir. The cells of this organism are straight to slightly curved rods that are gram negative and nonmotile. Spore formation has not been dem onstrated, Growth occurs at temperatures ranging from 28 to 60 degrees C, with optimum growth occurring at 55 degrees C, and at pH values ra nging from 5.5 to 8.6, with optimum growth occurring between pH 7 and 7.6. Growth occurs in media containing 0 to 20 g of NaCl per liter, an d optimum growth occurs in the presence of 10 g of NaCl per liter, Str ain RWcit2(T) grows on a range of organic acids, including citrate, py ruvate, malate, fumarate, and tartrate; on protein extracts; and on a limited number of carbohydrates. Sulfur, thiosulfate, and cystine are reduced to hydrogen sulfide, Sulfate, sulfite, and nitrate are not red uced. The DNA base composition is 34 mol% G+C, The 16S ribosomal DNA s equence revealed that strain RWcit2(T) is a member of the domain Bacte ria and forms a branch that is approximately equidistant from Dictyogl omus thermophilum and Thermoanaerobacter spp. (level of similarity, 82 %). Strain RWcit2(T) cannot be placed in any previously described taxo n based on its phylogenetic and physiological traits and is named Anae robaculum thermoterrenum gen. nov., sp, nov.,