ACTIVITY AND SPECIES COMPOSITION OF AEROBIC METHANOTROPHIC COMMUNITIES IN TUNDRA SOILS

The low-temperature, methane-oxidizing activities and species composit ion of methanotrophic communities in various tundra bog soils were inv estigated by radioisotopic and immunofluorescent methods. Methanotroph ic bacteria carried out the methane oxidation process through all hori zons of seasonally thawed layers down to permafrost. The highest activ ity of the process has been observed in the water surface layer of ove rmoistured soils and in water-logged moss covers. Up to 40% of (CH4)-C -14 added was converted into (CO2)-C-14, bacterial biomass, and organi c exometabolites. By immunofluoresecent analysis it was demonstrated t hat the representatives of I + X (Methvlomonas, Methylobacter, and Met hylococcus) and II (Methylosinus, Methylocystis) methanotrophic groups occurred simultaneously in all samples at 61.6% and 38.4%, respective ly. The number of methane-oxidizing bacteria in the ecosystems studied was 0.1-22.9 x 10(6) cells per gram of soil. Methanotrophic organisms ranged from 1% to 23% of the total bacterial number.