Restoration of urban agriculture soil by autochthonous fungal biodiversity

Abstract The persistence of PAHs in soil poses a significant challenge for common strategies of soil recovery, affecting, for instance, the general perception of urban agriculture, being highly exposed to different sources of pollution. Sustainable strategies for their mitigation are needed, such as mycoremediation, since it relies on fungi to transform pollutants into products with lower environmental burden. The current study investigates fungi of polluted soil, aimed at urban agriculture, with the intent of creating an active microbial consortium capable of transforming the pollutants of interest and decreasing the toxicity of the site. The analysis of key community members revealed a diverse mycobiota, mainly dominated by Ascomycota. Among the 28 isolated taxa and 16 genera, the most abundant ones were Aspergillus , Scedosporium , Trichoderma , and Fusarium . Fungal isolates were evaluated for their potential to grow in the presence of LMW and HMW PAHs, showing a significant difference due to inter- and intra-specific variabilities. Data showed that some fungi can also produce biosurfactants. Coupling this information with the capability of fungi to grow on carriers, six fungi were selected for in situ soil remediation. Biostimulation and bioaugmentation (with strains in co-cultures) were evaluated for pollutant mitigation. The best results were obtained by a microbial consortium that also revealed high tolerance to HMW PAHs. The chronic ecotoxicity of the soil did not show any effect on Eisenia fetida , with the only exception of biostimulation, which led to a 44% toxicity decrease. This study provides a foundation for fungal-based approaches for soil bioremediation and quality recovery, unveiling for the first time the capability of many species to inhabit PAHs-contaminated soil and be actively involved in their degradation. Key points • The microbiota of polluted soil was mainly dominated by Ascomycota. • The isolated 28 taxa mostly belong to Aspergillus, Scedosporium, Trichoderma, and Fusarium. • Many fungi degrade PAHs and/or produce biosurfactants. • A mix of millet and canary seeds worked as an efficient fungal carrier. • Biostimulation and bioaugmentation were tested against a PAHs-polluted soil.