Soil mycoremediation and the bacterial contribution to the depletion of total petroleum hydrocarbons.

An Ascomycetes, a Ciboria sp. strain, isolated from a dismissed refinery's polluted soil in Italy, was exploited for bioaugmentation in co-composting processes for the treatment of the soil of origin, contaminated by 8538 mg/Kg of total petroleum hydrocarbons. The fungal strain was inoculated at increasing percentages, 1 and 7%, on a fresh weight base ratio. In 90 days of incubation, the depletion of the contamination achieved was of the 99% and 78% with the 7% and 1% of fungal inoculum respectively. A high-throughput sequencing approach was adopted to study the soil microbial ecology during the process of decontamination. The metabarcoding of the bacterial and fungal communities was performed in order to evaluate the synergism between fungi and bacteria in the process. The functional metagenomic prediction indicated that the bacterial community was capable to transform both the aromatic and saturated fraction of the total petroleum hydrocarbons. Among the bacteria showing these features, generalist actinobacterial saprophytes resulted to be mandatory for the onset of the specialist bacterial species, involved in the total petroleum hydrocarbon depletion. The fungal metabolism accelerated the onset of specialist over generalist bacteria. The capacity of the Ciboria sp. to deplete total petroleum hydrocarbons in the soil in treatment was envisaged.