Transformation and degradation of synthetic organic compounds in soil occurs basically under the influence of microorganisms. In the present studies the interactions of soil microorganisms and water insoluble acaricide azobenzene were investigated. Azobenzene is a volatile orange-coloured crystalline substance with the acaricide and insecticide effects. The influence of azobenzene on the biomass of soil bacteria and the succession of heterotrophic bacteria were studied. Microbiological analyses showed that azobenzene in concentration up to 50 mg kg-1 of soil did not have any substantial effect on the total number and qualitative composition of soil bacteria.
The spatial distribution of soil microorganisms was studied using a modified glass slide technique of Kholodny-Rossi. Analysis of the microbial distribution on glass slides placed in soil showed an interaction between azobenzene and microbial spatial distribution. A specific microflora developed on the surface of azobenzene particles and caused the degradation of azobenzene crystals into amorphous mass. Accumulation of azobenzene in the microbial colonies was observed. It was shown that the bacteria isolated from the glass slides and soil were able to assimilate azobenzene in the presence of carbohydrates.