In modern agriculture, pesticides are frequently used in the field to increase crop production. Besides combating insect pests, insecticides also affect the population and activity of beneficial microbial communities in soil. Microorganisms are widely applied test-species in different bioassays because of the ease and low costs of their culturing as well as the lack of ethical issues often accompanying the use of higher organisms Proteases are a group of enzymes that belong to one of the four major classes of proteolytic enzymes and are generated by a variety of organisms including viruses, bacteria, protozoa, yeasts, plants, helminthes, insects and mammals. The proteases are widespread group of enzymes that catalyze the hydrolysis of different proteins and perform a pivotal role in the degradation and turnover of intracellular proteins.. In the present study Pseudomonas aeruginosa were exposed to methomyl of concentrations ranging from 10-7 M to 10-3 M for a period of 96 hrs and protease activity was evaluated at regular intervals of 24, 48, 72 and 96 hrs. The results indicated that protease activity increased with the increase in the dose and duration of exposure of methomyl in Pseudomonas aeruginosa and that protease is dose and duration dependent.
