CHARACTERISTICS OF ORGANIC MATTER COMPOSITION IN MICROBIAL MATS OF ALKALINE WATER ECOSYSTEMS OF THE BAIKAL REGION
High values of pH, mineralization and water temperature in alkaline water bodies are favorable environments for the development of microbial mats, where the primary producers of organic matter are cyanobacteria. The author studied the content of the organic (organic carbon, protein, carbohydrates) matter and isotopic composition of carbon in cyanobacterial mats of the soda lakes (Hilganta, Upper Beloye), and the alkaline thermal springs (Garga, Seyuya, Alla, Sukhaya) of the Baikal region. We found that cyanobacterial mats of extreme habitats are highly productive systems and organic carbon content reaches 25%. The composition of the organic matter is dominated by carbohydrates (12,42–24,73 %), the largest number which is defined in the mats gidroterm. They perform structural, formative role, protecting the microbial community from adverse environmental conditions. The amount of protein in the studied samples is of 5.92 % is 15.79 %. Organic matter in the mats is depleted by heavy isotope form 13С. It is revealed that photosynthetic mats of soda lakes in productional processes use biogenic carbon dioxide, whereas microorganisms of the alkaline hot springs use atmospheric and volcanic CO2. Organic carbon in the microbial mats of the methane hot spring Sukhaya is characterized by low isotopic content of 13С relative to mats biomass of the hot springs.