Impact of Pesticide (Chlorpyriphos) on Soil Microbial Diversity

The microbial mineralization of organic compounds and associated biotransformations such as nutrient dynamics and their bioavailability are adversely affected by the pesticides. The applied pesticides also reduce soil enzymatic activities that act as a ‘‘biological index’’ of soil fertility and biological processes in the soil environment. Microbial biomass is an important indicator of microbial activities and provides direct assessment of the linkage between microbial activities and  nutrient transformations. Pesticides are extensively used in agriculture as a part of pest control strategies. Owing to their xenobiotics characteristics, pesticides may adversely affect the proliferation of beneficial soil microorganisms and their associated bio-transformation in the soil. The applied pesticides may harm the indigenous microorganisms, disturb soil ecosystem, and thus, may affect human health by entering in the food chain. Collected soil samples were serially diluted up to 10-7 dilution. The diluted soil sample were inoculated on NA and PDA medium by using spread plate technique under aseptic conditions and incubated at 37°C and 26°C temperature for optimum growth. Three selected microbial strains were cultured onto MSL medium supplemented with chlorpyrifos at five concentrations (0, 50, 100, 150, 200 μg ml-1) for 12 days. In the non-contaminated soil both bacterial population and fungal population were higher. In contrast, in pesticide contaminated soil both populations were greatly suppressed. The bacterial population, in general is not able to survive and multiply well in presence of pesticide.