Altered fungal communities in contaminated soils from French industrial brownfields

Polycyclic aromatic hydrocarbons (PAHs) and metals are contaminants of industrial brownfield soils. Pollutants can have harmful effects on fungi, which are major actors of soil functioning. Our objective was to highlight fungal selection following long-term contamination of soils. Fungal diversity was assessed on 30 top-soil samples from ten sites gathered in three groups with different contamination levels and physico-chemical characteristics: 1) uncontaminated controls, 2) slag heaps displaying high PAH and moderate metal contaminations, and 3) settling ponds displaying high metal and intermediate PAH contaminations. Although fungal abundance and richness were similar among the soil groups, the diversity and evenness indices were lower for the slag heap group. Fungal diversity differed among soil groups at the phylum and OTU levels, and indicator species were identified. The relative abundance of Agaricomycetes, Saccharomycetes, Leotiomycetes and Chytridiomycota was higher in the control soils than in the two groups of contaminated soils. Cryptomycota LKM11 representatives were favoured in the slag heap and settling pond groups, and their relative abundance was correlated to the zinc and lead contamination levels. Dothideomycetes - positively linked to PAH contamination - and Eurotiomycetes were specific to the slag heap group. Pucciniomycetes and especially Gymnosporangium members were favoured in the settling pond soils.