Distribution and number of cultured bacteria of the phosphorus cycle in the ecosystem of Lake Baikal

Abstract

The study of cultured bacteria of the phosphorus cycle in biotopes of Lake Baikal (water column, surface microlayer of water, epilithic biofilms and bottom sediments) revealed uneven distribution over areas, biotopes and groups of microorganisms. Therefore, in biofilms and water column, phosphatase active bacteria prevail over phosphate solubilizing bacteria on average by an order of magnitude, whereas in the bottom sediments, their number is comparable. In the bottom sediments of the southern basin of the lake (the Selenga shallow waters), the number of bacteria of the phosphorus cycle (1461 CFU/cm³) is three times higher than in the northern part (463 CFU/cm³). The maximum number of phosphatase active bacteria was detected in epilithic biofilms, 39 251 CFU/cm³, and the minimum number was in the water column, 65 CFU/cm³. Phosphate solubilizing bacteria numerically prevail in the bottom sediments (915 CFU/cm³) and biofilms (900 CFU/cm³); the minimum number is typical of the water column (2 CFU/cm³). The occurrence of phosphate solubilizing bacteria in the studied biotopes varied from 46% to 97%, with a 100% occurrence of phosphatase active bacteria.