[Thermophilic and thermotolerant bacteria that assimilate methane]

Microorganisms assimilating methane at temperatures above 40 degrees C were isolated from various natural sources: ooze, mud, waste water of coal pits. The bacteria are obligate methylotrophs and are represented by two groups: (a) thermotolerant, growing at 37 to 45 degrees C; and (b) thermophilic, growing at 50 to 62 degrees C. The selective factor used to isolate various physiological forms of methylotrophs is corresponding temperatures of growth which allow to isolate from the same substrate meso-, thermotolerant, and thermophilic forms. Morphological and physiological properties of the strains are described. The thermotolerant cultures of methylotrophs are similar to Methylobacter vinelandii, though differ from it by some characteristics. The thermophilic microorganisms should be classed as a separate species Methylococcus thermophilus.