Isolation and Culture Conditions of a Thermophilic Methane-oxidizing Bacterium

Abstract

A new thermophilic methane-oxidizing bacterium (strain H-2) was isolated from a gas field. The organism grew at 30-55°C, and the optimum temperature for growth was 50°C. Methane was the sole carbon and energy source for growth, and no growth occurred on nutrient broth. When cultivated in a mixed culture with another kind of bacterium (Bacillus sp.), H-2 grew better on methane than in pure culture. Effects of gas composition, nitrogen sources, trace metals and vitamins on growth were studied. Cupric sulfate was found to be essential for growth of a pure culture of strain H-2, and vitamin B₁₂ stimulated its growth. Under the optimum culture conditions, the doubling times of mixed and pure culture were about 2 and 3hr, respectively.