Enhanced DDT degradation in aged soils via fungal treatment and surfactant application

Dichlorodiphenyltrichloroethane (DDT) is a legacy pesticide that, despite decades of discontinued use, remains in soils worldwide, posing long-term risks to ecosystems and human health. This study investigated the mycoremediation potential of 5 fungal species in historically contaminated forest nursery soils from Sweden, focusing on the degradation of DDT and its transformation products (collectively referred to as DDX). Aged, contaminated soils were incubated with fungi and a lignocellulosic substrate (straw) for 30 days in petri dishes. Pholiota adiposa, Trametes versicolor and Pleurotus ostreatus achieved the DDX degradation at 80 ± 3%, 72 ± 8%, and 69 ± 3% respectively, while Hypholoma fasciculare achieved lower degradation (45 ± 15%), and Agaricus bisporus showed no significant degradation. A complementary experiment, where the same soils were exposed to a liquid solution of enzymes from P. ostreatus for 8 days demonstrated that the addition of the surfactant Tween 80 mobilized soil-bound DDX into aqueous solution, where degradation by P. ostreatus enzymes occurred. Tween 80 also enhanced ligninolytic enzyme activity, suggesting synergistic effects on DDX degradation. This is the first study to compare bioremediation performance of multiple white-rot fungi of DDT in historically contaminated field soil using up-scalable and environmentally relevant conditions. Its findings support the use of selected ligninolytic fungi and amendment with the surfactant Tween 80, and therefore provides a basis for future environmental remediation.