Aerobic methanotrophs from the coastal thermal springs of Lake Baikal

Abstract

The number, activity, and diversity of aerobic methanotrophic bacteria in the sediments of three coastal thermal springs of Lake Baikal were analyzed. The average number of methanotrophs was 103–104 cells per 1 cm3 of sediment. The highest number of methanotrophs (108 cells/cm3 of silt) and the highest potential rate of methane uptake [7.7 nmol CH4/(cm3 day)] were revealed in sediments from the Sukhaya thermal spring. The methods of molecular ecology (DGGE, FISH, analysis of pmoA gene fragments) showed the predominance in most enrichment cultures of methanotrophs of type II, i.e., of the genera Methylocystis and Methylosinus. In only one enrichment culture (from the Sukhaya thermal spring), a type I methanotroph was revealed; its similarity to Methylococcus capsulatus Bath did not exceed 80%. These results demonstrate a widespread occurrence and high activity of the aerobic methanotrophic community in the coastal thermal springs of Lake Baikal.