PCBs for their physical and chemical properties are used in different industrial sectors; waste products and inadequate storage have polluted environments such as soils and water that endanger ecosystem survival. However, some living beings are able to adapt. Polychlorinated biphenyls (PCBs) are organic synthetic hydrocarbon compounds formed by two benzene rings bonded by a carbon bond, comprise a class of 209 individual compounds, isomers and congeners. Its objective was the isolation and identification of filamentous fungi capable of tolerating and adapting to survive in adverse conditions in the soil ecosystem contaminated by the xenobiotic PCBs, present in used dielectric oils (ADU) in an industrial sector of Barranquilla. The isolated fungi of the genus Aspergillus sp, Alternaria sp, Phoma sp, Rhizopus sp. survived concentrations of 20% ADU, and 200 ppm of PCBs.