Enhancing pesticide degradation using indigenous microorganisms isolated under high pesticide load in bioremediation systems with vermicomposts

•Vermicomposts as an alternative to peat in biobed bioremediation systems (BBSs).•Vermicompost BBSs as source of bacteria and fungi pesticide degraders.•The best fungus growth was in the BBSs with vermicompost from olive mill wastes.•Enhanced biodegradation of tebuconazole, oxyfluorfen and metalaxyl by bioaugmentation.•Four metabolites of oxyfluorfen and one of metalaxyl determined by GC/MS.

In biobed bioremediation systems (BBSs) with vermicomposts exposed to a high load of pesticides, 6 bacteria and 4 fungus strains were isolated, identified, and investigated to enhance the removal of pesticides. Three different mixtures of BBSs composed of vermicomposts made from greenhouse (GM), olive-mill (OM) and winery (WM) wastes were contaminated, inoculated, and incubated for one month (GMI, OMI and WMI). The inoculums maintenance was evaluated by DGGE and Q-PCR. Pesticides were monitored by HPLC-DAD. The highest bacterial and fungal abundance was observed in WMI and OMI respectively. In WMI, the consortia improved the removal of tebuconazole, metalaxyl, and oxyfluorfen by 1.6-, 3.8-, and 7.7-fold, respectively. The dissipation of oxyfluorfen was also accelerated in OMI, with less than 30% remaining after 30 d. One metabolite for metalaxyl and 4 for oxyfluorfen were identified by GC–MS. The isolates could be suitable to improve the efficiency of bioremediation systems.

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