Elimination of fungicides in biopurification systems: Effect of fungal bioaugmentation on removal performance and microbial community structure

Abstract

Bioaugmentation with ligninolytic fungi represents a potential way to improve the performance of biomixtures used in biopurification systems for the treatment of pesticide-containing agricultural wastewater. The fungus Trametes versicolor was employed in the bioaugmentation of a biomixture to be used in the simultaneous removal of seven fungicides. Liquid cultures of the fungus were able to remove tebuconazole, while no evidence of carbendazim, metalaxyl and triadimenol depletion was found. When applied in the biomixture, the bioaugmented matrix failed to remove all the triazole fungicides (including tebuconazole) under the assayed conditions, but was efficient to eliminate carbendazim, edifenphos and metalaxyl (the latter only after a second pesticide application). The re-addition of pesticides markedly increased the elimination of carbendazim and metalaxyl; nonetheless, no clear enhancement of the biomixture performance could be ascribed to fungal bioaugmentation, not even after the re-inoculation of fungal biomass. Detoxification efficiently took place in the biomixture (9 d after pesticide applications) according to acute tests on Daphnia magna. DGGE-analysis revealed only moderate time-divergence in bacterial and fungal communities, and a weak establishment of T. versicolor in the matrix. Data suggest that the non-bioaugmented biomixture is useful for the treatment of fungicides other than triazoles.