Thermoanaerobacter tengcongensis sp nov., a novel anaerobic, saccharolytic, thermophilic bacterium isolated from a hot spring in Tengcong, China

A new, extremely thermophilic bacterium, designated strain MB4(T), was isol ated from a Chinese hot spring. The new isolate was an obligately anaerobic , rod-shaped, Gram-negative, saccharolytic bacterium. Spore formation was n ot observed. Growth occurred at temperatures between 50 and 80 degreesC, wi th an optimum of around 75 degreesC; at ph values between 5.5 and 9.0, with an optimum of 7.0-7.5; and at salinities between 0 and 2.5 % NaCl, with an optimum of around 0.2 % NaCl. The organism utilized glucose, galactose, ma ltose, cellobiose, mannose, fructose, lactose, mannitol and starch. Acetate was the main end product from glucose fermentation. Thiosulfate and sulfur were reduced to hydrogen sulfide. Sulfate, sulfite and nitrate were not re duced. Growth was inhibited by hydrogen. The G+C content of the DNA was 33 mol%. Phylogenetic analyses based on the 16S rDNA sequence indicated that t he isolate was a new member of the genus Thermoanaerobacter and formed a mo nophyletic unit within the Thermoanaerobacter cluster. Based on its phenoty pic and phylogenetic characteristics, the isolate was proposed as a new spe cies, Thermoanaerobacter tengcongensis. The type strain is MB4T (= Chinese Collection of Microorganisms AS 1.2430(T) = JCM 11007(T)).