ISOLATION OF AN EXTREMELY THERMOPHILIC CHEMOORGANOTROPHIC ANAEROBE SIMILAR TO DICTYOGLOMUS-THERMOPHILUM FROM NEW-ZEALAND HOT-SPRINGS

A strain similar to Dictyoglomus thermophilum, isolated from a New Zealand hot spring, is described. This strictly anaerobic, Gram-negative, non-motile and non-sporulating bacterium usually exists as long thin filaments of 5 to 25 .mu.m by 0.35 to 0.45 .mu.m. Rotund bodies are commonly observed. Thin sections of the cells revealed a two-layered cell wall. The optimum texture and pH for growth was 70.degree. C and 7.0 and 7.5 respectively. No growth was observed at 40.degree. C and 85.degree. C or at pH 4.5 to pH 9.0. The organism fermented glucose, maltose, mannose, xylose, lactose, cellobiose, galactose and sucrose and produced acetates as the major end-product with significant amounts of lactate, H2 and O2 and only traces of ethanol. The doubling time on glucose was 10 h. The DNA base composition was 29.5% guanine plus cytosine as determined by the thermal denaturation method. Growth was inhibited by penicillin, tetracycline and chloramphenicol indicating that the organism was a eubacterium. These features are in common with the newly described species Dictyoglomus thermophilum to which the New Zealand isolate belongs.