Rhizo-bioremediation of DDT-contaminated soils

Developing an inexpensive, effective and environmentally-friendly method of remediation of persistent organic pollutants is still an emerging need. Exploiting natural rhizosphere microorganisms, having capacity to degrade various xenobiotics, in association to plants able to accumulate the pollutants into their biomass, is a promising alternative to conventional remediation techniques. In this respect, fungi can play a key role. Several reports are showing high potential of Cucurbitaceae in phytoremediation of DDT and its metabolites. In this study we present the results of rhizo-bioremediation of DDT using different varieties of Cucurbita pepo, inoculated in pot experiments with three fungal strains, isolated from DDT-contaminated soils in Poland, belonging to Trichoderma, Rhizopus and Mortierella genera. All the tested strains induced an increased uptake of DDT residues, either in case of “old” or recent contamination of the soil, in the C. pepo plants, thus reducing the content in the rhizospheric soil (about 50-60%) in comparison to control plants. The applied microfungi seemed also to influence the translocation of DDT from roots to the upper parts of the plant. Nevertheless, we did not detect DDT residues in the edible parts (fruit) of C. pepo. The proposed co-remediation strategy is discussed in view of possible interactions between plant genotypes and fungal strains that can affect the efficacy and/or mechanisms of this promising method of bioremediation. The work was supported by a grant of the Polish Ministry of Agriculture and Rural Development.