Microorganisms isolated from polluted urban soils highly effectives in degrading recalcitrant pesticides

The neighborhood of Moravia in Medellin (Colombia) is home to a vast population of people and is known for its highly contaminated soils. Between 1972 and 1984 all types of solid waste from the city of Medellin were deposited in the area, which had no technical specifications for a landfill. Domestic, hospital and industrial waste was therefore allowed to accumulate and many of the area’s residents made a living by recycling. A diagnosis carried out by the GDCON Group at the University of Antioquia between 2004 and 2005 and funded by the Area metropiltana del valle de Aburra, it was found that leachate from the mountain of Moravia, had heavy metals, phenols, sulphides, benzene, toluene, xylene, etc. In another study carried out by the GDCON and National University of Colombia (Medellin) between 2007 and 2009, it was found that plants and animals (mice, cockroaches) of Moravia also contained these toxic pollutants. For this reason, the government of Medellin decided to move the people living in Moravia to another site in Medellin (between 2010 and 2014). Microbial consortia isolated from Moravia soils (MS) showed that had a high capacity to degrade pesticides chlorpyrifos, methyl parathion and malathion (20, 30 and 130 mg Kg -1 ). For a point of comparison, the degradation of the 3 pesticides was also performed with isolated pools of immature compost. The MS microbial consortia showed higher degradation rates than CI microbial consortia when malathion, methyl parathion and chlorpyrifos were degraded.