The role of microplastic on ecosystem functioning - a focus on antibiotic resistance spread in input for agricultural purposes

The misuse and overuse of antibiotics for medical, but also non medical purposes, has resulted in a substantial increase in the rates of antibiotics release into the environment, and hence the growth of drug resistance in bacterial strains, with an impact on both the environment and human health. Microplastic pollution may be a major stressor on the environment, causing relevant ecological implications. Previous research have shown that synthetic polymer particles (diameter < 5mm) can be found worldwide, from the arctic sea ice, to the waters of mountain lakes, to agricultural soils representing new submerged surfaces for microrganisms colonization, pollutant dispersal, nutrient cycling, but mostly biofilm formation. More over, on this microparticles, Horizontal Gene Transfer (HGT) between different bacteria is enhanced, favouring the transfer of pathogenicity and antibiotic resistance in the environment. Agricultural practices like irrigation and amendment are considered to be significant microplastic transportation pathways and antibiotic resistance. However, still little is know about the microbiological activity involved. In this context, I propose an inclusive study with a multidisciplinary approach to solve this gap highlighting the role of microplastics/antibiotics in the spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG), in relation to agricultural practices, natural environments, food webs and human health. In particular, I will set-up microcosms with three products intended for agricultural purposes: Irrigation water and its suspended solids; compost; manure. These samples will be collected both from a warm climate area (Foggia, South Italy) and from a colder one (Val Venosta, North Italy; Tromso, Norway). Then, microplastics and antibiotics will be added, and the microcosms will be incubated at different temperatures according to the area. The project will last two months to understand the temporal variation of microbial community composition, metabolism and overall functionality, mostly related to the resistances and the evironmental services promoted by microorganisms. The study will highlight possible differences due to the sample type in correlation with the environmental conditions.