Food Microbiology

Groundwater filtration by rapid sand filters (RSF) at waterworks is a widespread technology for drinking water production, which efficiently removes the naturally occurring pollutants (e.g., NH4) by a combination of chemical and biological (microbial) processes. During the past few decades, unnatural toxic substances, pesticides, have appeared in groundwater, which challenges the future stable supply of drinking water to consumers. The aim of current project was to develop an environmentally friendly biotechnology dealing with pesticides in ground- and drinking water. The biotechnology is based on natural microorganisms in RSF, possessing the abilities to degrade pesticides toward CO2 and H2O. These skills are frequently located on mobile genetic elements (MGE), which bacteria exchange among themselves. Application of natural isolates with pesticide-degrading genes on mobile genetic elements (MGEP) would ensure transfer and permanent establishment of introduced MGEP among the native microbial communities. Hence, the Trojan Horse biotechnology`s omits the well-known limitations of low-to-none survival of exogenously introduced pollutant degrading bacteria in the environment. Results shown that prolonged (½ year) exposure of sand material to investigated pesticides enhanced the fraction of pesticide-degrading bacteria in enrichments, ensuring isolation. Pesticides effected the structure of microbial communities, reducing abundance of e.g. Alpha Proteobacteria and Nitrospira sp. by MCPP, or stimulation Springobacteriia sp. by glyphosate. Suitability of Trojan Horse concept was confirmed by experiments combining plasmid-borne reporter (gfp) gene and flow-cytometric approach, revealing dominance of Alpha-, Beta- and Gamma Proteobacteria among native sand filter bacteria that acquired investigated plasmid (MGE).