A number of studies in the 1980s and 1990s showed that crop-protection products, applied to drained fields, couldmove downwards through the soil profile and to the groundwater. Organophosphorus insecticides (OPs) are usedall over the world for crop protection, for other agricultural practices such as sheep dipping and, in aquaculture, forthe control of sea lice. Ops besides showing a specific neurotoxicity and have also been related to various moderndiseases, including Creutzfeldt–Jakob (CJD) and the Gulf War syndrome. Although OPs are less persistent thanOrganoclorine pesticides (OCs), they still constitute an environmental risks thus increasing the social concernabout their levels in soils, surface waters, and ground waters. Degradation of OPs by microorganisms hasbeen assessed for a few bacterial strains. In the present study the OPs degrading potential of indigenous soilmicroorganisms was investigated.Using enrichment cultures in which parathion was the only C and energy sources many bacterial strains wereisolated from OPs contaminated and pristine agricultural soils characterized by different physico-chemicalproperties. More than 40 potential OPs degraders were isolated and grouped in operational taxonomic units (OTU)using analysis of polymorphism showed by the ribosomal internal transcribed spacer (ITS). Partial sequencing of16S rRNA gene of representative isolates of each OTU revealed that most of them belong to Proteobacteria andActinobacteria. All the analyzed soils showed the presence of putative OPs degraders: the highest diversity wasfound in organic cultivated soils, the lowest in chemically cultivated soils.Degradation of different OPs, characterized by different physical and chemical properties, was obtained bydifferent selected representative strains using SPME GC-MS analysis on water and soil microcosms. The resultsshowed that, after the incubation period, the amount of pesticide residues were in the range 20-80%. Some of theisolates bacterial species are currently unknown as OPs degraders.
|Stato di pubblicazione||Published - 2009|