A study in the experimental conditions of pesticide action on microorganisms characterizing sanitary-epidemiological safety of reservoirs

Abstract

The paper presents experimental data on the pesticides action (molinate (OrdramA), Dinitroortocresolum and chlorophos) at concentrations of 0.01 mg /l to 10 mg/l on sanitary-indicative (TBC, total coliform bacteria, E. coli, E. faecalis), potentially pathogenic ( Ps. aeruginosa) and pathogenic (S. Derby) microflora of the river water. As the test cultures there were used isolated from the reservoir and museum strains of microorganisms. Due to the fact that the rate of decomposition ofpesticides in water increases in direct proportion to the extent of its biological contamination, the experiments were performed with the river water: native and sterilized by autoclaving. There were identified species and strain differences in the microbial response to the action of pesticides. The selectivity of OrdramA action at a concentration of 0.1 to 10 mg/l on Salmonella and of chlorophos at a concentration of 10 mg/l for Salmonella and E. coli is manifested in the stimulation of the reproduction of these bacteria. Dinitroortocresolum in concentrations of 10 mg/l and 1 mg/l gives rise in the reproduction of Pseudomonas aeruginosa and inhibits the growth of total coliform bacteria and E. coli, in a concentration of 0.1 mg/l the preparation stimulates the viability of all the studied microorganisms. When entering the body of water, pesticides were found to cause changes of biocenosis in the river water and disturb bacterial self-cleaning processes. In conditions of pesticide pollution total coliform bacteria, E. coli and E. faecalis unable to maintain their indicative value and therefore the use of only them for the evaluation of the sanitary-epidemiological status of the water source appears to be insufficient. Due to the fact that the epidemic potential of water is directly dependent on quantitative content ofpathogenic and opportunistic pathogenic microorganisms in it, the reproduction Salmonella and Pseudomonas bacteria is a negative moment from the sanitary and epidemiological point of view.