The role of free extracellular dna in determining the environmental antibiotic resistome
Free extracellular DNA (FED) is DNA dissolved in waters and in soils, where it arrives after being excreted by living
organisms or following the disruption of living cells. FED can be the most prominent fraction of DNA in waters subjected to
strong disturbances, where the mortality rate of microorganisms is high, e.g. wastewater treatment plants effluents. FED are
composed by a variety of DNA fragments including resistance genes and mobile elements. There are early evidences than
FED can represent a very important, although neglected, source of antibiotic resistance genes (ARGs) in the environment,
where the bacterial community can access FED and incorporate extracellular DNA by horizontal gene transfer.
If this process will be confirmed and quantified by dedicated researches, our understanding of the cycle of antibiotic
resistances into the environment and back to human pathogens could change dramatically, calling for a whole rethinking of
the wastewater treatments nowadays applied. The Project REDTEAR will tackle the issue and will clarify the role of FED in
the spread and the persistence of ARGs in open waters in central Europe, offering a unique opportunity for a correct
management of this problem, already identified as one of the major challenges for human health in the next century.