Fungi to face HCH-pollution: precious bioresources for soil remediation

Hexachlorocyclohexane (HCH) is a persistent organic pollutant of global concern, posing severe risks for human health and ecosystem functioning. Mycoremediation represents a feasible nature-based solution for the remediation of HCH-contaminated soils thanks to the ability of fungi to tolerate, bioaccumulate and biodegrade it. A contaminated site by HCH and toxic elements in the National Priority Site “Bacino del Fiume Sacco” within the Metropolitan City of Rome was selected. Soil cores up to 1 m of depth were collected from 2 plots, each one divided in topsoil and subsoil samples. Fungi from soil samples were isolated in enrichment conditions, providing an isomer mixture (α-, β-, γ-, and δ-HCH) at high concentrations to select exclusively those capable of effectively tolerating and utilizing them as a sole C-source. From all the processed samples up to now, a total of 49 fungal strains were isolated, mostly belonging to Fusarium and Alternaria genera. Moreover, the quantification of the culturable fungal load of the processed samples has been evaluated through a conventional isolation procedure. Finally, the evaluation of the capacity of strains to produce biosurfactants, useful metabolites boosting HCH biodegradability, was performed by emulsification activity test, oil displacement test and drop collapsing assay. The results of the assays showed a clear ability of some strains to produce biosurfactants, making them suitable candidates for further tests on HCH biodegradation.