As part of the OHEJP project FED-AMR, twelve European partner organizations are investigating the role of free extracellular DNA in the spread of antimicrobial resistance across ecosystem boundaries, along the food/feed chain. The contribution of bacterial transformation to horizontal gene transfer (HGT) of antimicrobial resistance genes (ARGs) in environments critical to both human and animal health is currently unclear.

Extracellular DNA, or exDNA, is ubiquitous and persistent in natural environments. Free exDNA has been identified as a source of ARGs in, for example, manure, wastewater, feed, but also food. Furthermore, free exDNA is an important matrix constituent of bacterial biofilms. This can be detected in the gastrointestinal tract of mammals and in feces. ExDNA is ubiquitous and sufficiently stable in the natural environment, which is why it can form an important reservoir for ARGs.

ARGs spread by natural genetic transformation of environmental bacteria, as well as animal and human pathogens. This naturally occurring bacterial transformation is an HGT process. The exDNA is believed to be a major contributor to the environmental resistome, as up to 60 percent of the DNA extracted from soil is derived from extracellular sources. Furthermore, transformation plays a crucial role in the formation of mosaic ARGs,.

No physical contact is required between donor and recipient bacteria during natural transformation, resulting in a large temporal-spatial separation between the source and recipient of genetic information and regulated exclusively by the recipient cell. These conditions facilitate ARGs to overcome ecosystem barriers and invade new ecosystems. The project will draw on elements of the EFFORT project and incorporate the "One Health" approach. Among other things, agricultural soils, water samples, feed and food will be studied.