Bioremediation Performance of Two Telluric Saprotrophic Fungi, Penicillium Brasilianum and Fusarium Solani, in Aged Dioxin-contaminated Soil Microcosms

In this study, 28 strains of filamentous fungi were isolated from soil that were historically contaminated with polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs; northern France). These fungal isolates were selected for their ability to use hexadecane as the sole carbon source and for hydrophobic molecule behavior. Six strains produced significant dry biomass (> 25 mg) on hexadecane: Paecilomyces carneus, Penicillium brasilianum, Absidia glauca, Lecanicillium lecanii, Mortierella minutissima, and Bionectria ochroleuca. In a second experiment, P. brasilianum and F. solani were tested for their ability to dissipate 17 PCDD/F congeners in non-sterile contaminated soil microcosms using olive oil as an unconventional carbon source. After two months of incubation, P. brasilianum significantly reduced the soils' toxicity equivalency (TEQ) by 35%. The F. solani treatment led to a significant reduction (approximately 25%) in PCDD/F concentrations. Statistical agglomerative hierarchical clustering analysis indicated that using cardboard as a growing medium and bulking agent is more efficient than using poplar wood. As fungal dioxin dissipation can involve the production of reactive oxygen species or fungal P450-like enzymes, the potential role of these mechanisms deserve further study. However, the proposed approach could allow the development of cost-effective and eco-friendly (low technology) techniques to maintain the integrity of soils.

Automated summary

In this study, 28 strains of filamentous fungi were isolated from historically contaminated soil in northern France. Selected for their ability to use hexadecane as a sole carbon source and hydrophobic behavior, six strains showed significant dry biomass on hexadecane. Further experiments demonstrated the potential of P. brasilianum in reducing soil toxicity and F. solani in dissipating PCDD/F concentrations in contaminated soil microcosms. Additionally, the use of cardboard as a growing medium was found to be more efficient than poplar wood in this process. Further research is needed to explore the mechanisms involved in fungal dioxin dissipation.