[Importance of Bdellovibrio in regulating microbial cenoses and self-purification processes in domestic sewage].

The bacterial parasite Bdellovibrio was directly proved to be involved in the regulation of microbial cenoses and in the self-purification of domestic waste waters. The incidence of heterotrophs, Gram-negative bacteria, E. coli and Bdellovibrio was followed up in dynamics in the microecological system of waste waters for ten days. In control experiments, bdellovibrions were removed using pteridine as a vibriostatic agent. In the absence of bdellovibrions, the cell number of the studied microorganisms did not increase after reaching a stationary level. In the control, the total incidence of heterotrophs decreased 1355 times, that of Gram-negative bacteria fell down 527 times, and that of E. coli cells dropped 3419 times due to the interaction between the host bacteria and Bdellovibrio. The variations in the number of interacting cells were characteristic of a two-component parasite-host system.