A multiple pesticide resistant Bacillus cereus PR-2J isolated from paddy field - a potential strain for pesticide detoxification

The soil bacteria, residing under pesticide stress, are able to resist and detoxify these toxic pesticides into nontoxic products. The objective of the present study is to isolate and identify the bacteria highly resistant to multiple pesticides from cultivated paddy field. About 20 bacterial strains were isolated and screened against four different pesticides namely endosulfan, phorate, carbofuran and carbaryl. Out of them, seven strains showed resistance to all four pesticides at a concentration of 150 mg/l and the strain PR-2J was resistant to these pesticides even at concentration >2000 mg/l. The MIC tests for all the four pesticides showed that the strain PR-2J was susceptible to 2200, 3000, 2700 and 2700 mg/l of endosulfan, phorate, carbofuran and carbaryl respectively. The identification of the bacterium PR-2J was established on the basis of 16S rRNA gene sequencing and biochemical characterization which showed 99% 16S rDNA sequence similarity to the Bacillus cereus. This strain can not only grow in 200-500 mg/l of each pesticide without any growth inhibition, but it is also able to grow in a mixture of all four pesticides at 1000 mg/l concentration. PR-2J is also able to utilize pesticides as a carbon source in mineral salts minimal media. So, the isolated bacterium PR-2J is an excellent pesticide resistant strain of Bacillus sp. which may be deployed in the bioremediation of multiple pesticidecontaminated sites.