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

Abstract

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 × 10³ CFU/cm²); amylolytics (38.1 ± 7.7 × 10³ CFU/cm²); phosphate-solubilizing microorganisms (4.8 ± 1.4 × 10³ CFU/cm²); phosphate-mobilizing microorganisms (212.0 ± 27.6 × 10³ CFU/cm²); phenol-oxidizing microorganisms (15.7 ± 2.4 × 10³ CFU/cm²); molds (3.2 ± 0.4 × 10³ CFU/cm²); and total coliform bacteria (193.3 ± 28.2 CFU/cm²), with the total microbial abundance (TMA at 37°C) of 24.9 ± 1.7 × 10³ CFU/cm², 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.