Role of Cultured Microorganisms from Biofilms Formed on Rocky Substrates in the Lake Baikal Self-Purification System

Differences in the quantitative and qualitative compositions of various physiological and biochemical groups of cultured microorganisms were revealed in biofilms formed on stony substrates in the littoral zone of Southern Baikal (August 2012) in the areas with different anthropogenic load. Maximal abundance of microorganisms was registered in epilithic biofilms from the area of Baikalsk Pulp and Paper Plant: organotrophs (770.2 ± 290.3 × 10 3 CFU/cm 2 ); amylolytics (38.1 ± 7.7 × 10 3 CFU/cm 2 ); phosphate-solubilizing microorganisms (4.8 ± 1.4 × 10 3 CFU/cm 2 ); phosphate-mobilizing microorganisms (212.0 ± 27.6 × 10 3 CFU/cm 2 ); phenol-oxidizing microorganisms (15.7 ± 2.4 × 10 3 CFU/cm 2 ); molds (3.2 ± 0.4 × 10 3 CFU/cm 2 ); and total coliform bacteria (193.3 ± 28.2 CFU/cm 2 ), with the total microbial abundance (TMA at 37°C) of 24.9 ± 1.7 × 10 3 CFU/cm 2 , which indicated high degrading activity of the biofilms in response to the anthropogenic load in the area. Epilithic biofilms of the Bol’shie Koty area exhibited the lowest abundance of organotrophic and phosphate-solubilizing microorganisms, while molds were absent.