[Participation of bdellovibrios in sewage self-purification processes]

The participation of bacterial parasites belonging to the genus Bdellovibrio in the processes of sewage self-purification was studied in refineries of Pushchino. The lytic activity of Bdellovibrio resulting in a decrease of the number of heterotrophic Gram-negative bacteria and E. coli in sewage was found to depend on the temperature factor influencing the intensity of interaction between the parasite and the host bacterium. The maximal p/h (parasite/host) index was found at the water temperature of 26 degrees C and the minimal one at 19 degrees C. Sewage purified at 26 degrees C and transferred to a precipitation tank contained 800 cells of E. coli in 1 ml while that purified at 19 degrees C contained 4000 cells in 1 ml. The number of interacting organisms varied in sewage which was typical of the "parasite-host" relations. Therefore, Bdellovibrio should be involved in the self-purification of sewage from the intestinal microflora at 26 degrees C; to a lesser extent, at 23.5 degrees C; and not at all, at 19 degrees C.