Isolation of Bacteria from Agricultural Soils and Evaluation of Their Degradative Capacity for Organochlorine and Organophosphorus Pesticides

In this work, OP- and OC-degrading bacteria were isolated from agricultural soil samples taken in the department of Bolivar, Colombia. The objective of this research was to degrade organochlorine and organophosphorus pesticides using bacterial colonies native to agricultural soils. Two bacterial colonies were isolated from the soil samples, which showed a higher degree of adaptation to media contaminated with the pesticide mixtures. They were identified by biochemical tests using BBL Crystal kits, and, subsequently, their 16S rDNA was sequenced using the PCR technique. Bacterial growth was studied by the OD index, taking absorbance readings on a UV-VIS spectrophotometer at 600 nm, at the 0.5 McFarland scale, and quantification of pesticide degradation was studied by GC–MS. The colonies identified were Bacillus cereus and Paenibacillus lautus. B. cereus isolates were exposed to the OPs malathion, chlorpyrifos, and coumaphos [80 mg·L−1], degrading at rates of 52.4%, 78.8% and 79.5%, respectively, after 12 days of incubation in liquid medium at pH = 7.0 ± 0.2 and 37 °C. Furthermore, P. lautus isolates exposed to the OCs lindane, metolachlor, endrin, and p,p′-DDT [80 mg·L−1] degraded at rates of 64.0%, 60.8%, 55.7% and 65.1% under the same conditions of temperature, pH, and incubation time. These results show that B. cereus and P. lautus might be useful for cleaning up environments that have been polluted by OPs and OCs.