CHARACTERIZATION OF AN EXTREMELY THERMOPHILIC SULFUR-METABOLIZING ARCHAEBACTERIUM BELONGING TO THE THERMOCOCCALES

An extremely thermophilic, obligately anaerobic, sulphur-metabolizing archaebacterium of the order Thermococcales, previously isolated from a thermal pool at Kuirau Park, Rotorua, New Zealand, partially describ ed, and designated isolate ANI,Thermococcales was further characterize d. The isolate was a regular coccus of 0.5-2.0 mm in diameter, was str ictly anaerobic, chemoorganotrophic, and fermentative. Peptone, yeast extract, or casein served as carbon and nitrogen source, and a variety of amino acids and glucose, but not organic acids, carbohydrates, or other sugars supported growth in the presence of peptone (0.1%). Major metabolic end products were H-2, sulphide, acetate, isobutyrate, and isovalerate/2-methylbutyrate. Isolate ANI had a temperature optimum of 75-80 degrees C, a pH optimum of 7.4, and a sodium chloride concentra tion optimum of 50 mM. No growth was observed in the absence of sodium chloride (or lithium chloride) and sulphur (or cystine or oxidized gl utathione).