FLUXARG · From reservoirs to vectors: role of amoebae in antibiotic resistance gene transfer and aquatic microbial dynamics under global environmental factors

Antimicrobial resistance (AMR) has become a global threat and a major public health priority under the “One Health” approach. In particular, Aquatic environments affected by anthropogenic activities, represent a huge reservoir and potential hotspot for the spread of antibiotic resistance genes (ARGs), potentially via horizontal gene transfer (HGT) involving mobile genetic elements (MGEs). Current data suggests that free-living amoebae (FLA), which are often underestimated, could play a potential key role in the spread of AMR. FLA not only act as natural predators of bacteria but also serve as protective hosts for various pathogens, enhancing their survival and potential for HGT. Previous studies have shown that FLA are reservoirs for pathogenic bacteria and ARGs of major clinical interest. However, their exact role in the ARGs dissemination via HGT and the involvement of MGEs in this process remains poorly explored. The project FLUXARG aims to further investigate the role of amoebae as reservoirs of ARGs and their contribution to the transmission of ARGs in aquatic environments. By studying HGT between bacteria living in amoebae, we aim to understand how ARGs are spread in aquatic environments via FLA. In addition, FLUXARG will investigate the effect of abiotic factors, such as physicochemical parameters during seasonal variations, on the efficiency of HGT between intra-amoebic bacteria. In parallel, FLUXARG will assess how these interactions shape the composition and diversity of aquatic and amoebic microbiomes, leading to a better understanding of their ecological importance. To achieve these objectives, in FLUXARG, I will employ culture assays, high-throughput genomic and metagenomic techniques, and experimental microcosms to mimicking environmental conditions. The results will lead to a better understanding of the role of FLA in the persistence and spread of AMR, potentially guiding the development of effective strategies to mitigate this growing threat.