Thermophilic anaerobic spirochetes in New Zealand hot springs

Electron and light microscopy revealed the presence of spirochetes in New Zealand thermal springs. The spirochete population in one spring studied (Kuirau Lake) was affected by fluctuations in temperature and/or pool level. A pure culture of the strictly anaerobic bacterium revealed that it grew optimally at a temperature of 45–50°C, with no growth occurring above 60°C, and a pH of 7.0–7.5 with no growth occurring at pH 5.5 or 8.5. Growth was inhibited by chloramphenicol, penicillin, streptomycin, tetracycline and neomycin but not by d-cycloserine, novobiocin or phosphomycin at 10 µg/ml. A wide range of carbohydrates were utilized but not organic acids. Acetate was the major end product of glucose fermentation with substantial amounts of ethanol and traces of lactate being produced.