Effect of malathion on certain beneficial microbial activities in Egyptian soils

ABSTRACT

Malathion was incorporated into Azotobacter chrococcum growth medium with different concentrations up to 600 ppm. The increase in the insecticide concentrations gradually inhibited microbial growth and nitrogen fixation. Meanwhile, the fixed nitrogen continued to increase, for each concentration throughout the experimental period [30 days]. On the other hand, low doses of malathion [100 and 200 ppm] increased both viable count of Bacillus megaterium and its capability of dissolving rock phosphate all over the incubation periods [30 days]. Meanwhile, high doses [800 and 100 ppm] were deleterious to growth and mineralization activity of B. megaterium. The applied malathion up to 400 ppm completely disappeared at the end of the incubation period