FORMATION OF ENVIRONMENTAL RELATIONS BETWEEN ERYSIPELOTHRIX RHUSIOPATHIAE AND RICCIA FLUITANS IN HYDROBIOCENOSES

Purpose. To study ecological relationships between the pathogenic bacteria Erysipelothrix rhusiopathiae and Riccia fluitans. Methodology. Aqueous solutions of in vivo and post-lethal secretions of R.fluitans were sterilized by vacuum filtration through filters with pore diameter of 0.2 microns. After adding E. rhusiopathiae, the samples under study contained the secretions of Riccia fluitans in 1:10, 1:100, 1:1000 and 1:10000 dilutions. As a control, sterile tap water was used in a volume similar to the samples, in which the same amount of E. rhusiopathiae was added. After a 48-hour exposure, the test samples were taken to determine the density of bacterial populations. Findings. The substances, emitted by R. fluitans during the active growing period, are capable of producing a stimulating effect on E. rhusiopathiae populations only in low dilutions. As a result of degradation processes taking place after the death of R. fluitans, there is a production of substances, which E. rhusiopathiae bacteria can actively use to increase their density in the medium. In hydrobiocenoses, R. fluitans and E. rhusiopathiae form topical-type biotic relations; as a result, erysipelothrixes find favorable conditions to exist in thickets of this plant throughout the year. Originality. Environmental relations of E. rhusiopathiae with aquatic plant R. fluitans have been studied for the first time. Practical value. Pathogenic bacteria E. rhusiopathiae, being a part of freshwater ecosystems, can threaten humans and animals with infection. The environmental factors that influence the quantity and existence of erysipelothrix in reservoirs have important epidemiological and epizootic significance.