Increased production of pathogenic, airborne fungal spores in response to exposure to 2 chlorinated aromatic hydrocarbon pollutants

Organic pollutants are omnipresent and can penetrate all environmental niches. We evaluated the hypothesis that short-term (acute) exposure to aromatic hydrocarbon pollutants could increase the potential for fungal virulence. We analysed whether pentachlorophenol and triclosan pollution results in the production of airborne fungal spores with greater virulence than those derived from an unpolluted (Control) condition. Each pollutant altered the composition of the community of airborne spores, favouring an increase in strains with higher in vivo infection capacity (wax moth Galleria mellonella used as infection model). Fungi subsisting inside larvae, 72h post-infection and arising from either airborne spore-inoculum, exhibited comparable diversity (mainly within Aspergillus fumigatus). Several virulent Aspergillus strains were isolated from larvae infected with the airborne spores produced in a polluted environment. Meanwhile, strains isolated from the control, including one A. fumigatus strain, showed no virulence. Potential pathogenicity increased when two Aspergillus spp. virulent strains were assembled, suggesting the existence of synergisms that impact pathogenicity. None of the observed taxonomic or functional traits could separate the virulent from the avirulent strains. Our study emphasises pollution-stress as a possible driver of phenotypic adaptations that increase Aspergillus spp. pathogenicity as well as the need to better understand the interplay between pollution and fungal virulence.