Isolation and optimization of microbial consortia for the biodegradation of two persistent fluorinated fungicides

Microbial consortia capable of completely removing and defluorinating two persistent fluorinated fungicides, epoxiconazole (EPO) and fludioxonil (FLU), were enriched from an estuarine sediment and an agriculture soil. The enrichments were conducted along 6 months, during which the fungicides were supplemented individually to the cultures every 21 days at 5 mgL-1, using sodium acetate as a co-metabolite (fed twice a week at 400 mgL-1). Biodegradation of EPO and FLU was detected early on the enrichment phase and a gradual increase on their performances was observed throughout this period. After ca. 5 months, the complete removal and defluorination of EPO and FLU was observed for all cultures in a period of 10-15 days. These biodegradation efficiencies were found to be similar in the absence of a co-metabolite. The two pesticides were efficiently biodegraded at concentrations up to 10 mgL-1. By estimating the biodegradation kinetics of the enriched consortia, it was possible to determine half-life values significantly lower than those reported in the literature for these pesticides, rendering EPO and FLU as non-recalcitrant under these experimental conditions. 16S rDNA analysis showed that these consortia harbor bacteria belonging to the Proteobacteria phylum. Current work is focused on the optimization of the degrading consortia and on the elucidation of the metabolic pathways of these pesticides.