Seasonal and spatial distribution of antibiotic resistance genes in marine microbial communities along a trophic gradient in central Adriatic Sea

Bacterial resistance to antibiotics is declared by World Health Organization as ''one of the greatest threats to global health, food security and development today''. Natural environments, particularly aquatic ones, are among major sources/reservoirs of antibiotic resistance genes (ARGs). We still lack much to comprehend the overall span of ARG repertoire available in marine environment as well as the role of bacterial communities as their vehicles, particularly in terms of proliferation and further dissemination of ARGs towards human pathogenic bacteria. Thus, we aim to for the first time comprehensively and interdisciplinary investigate the resistance background in planktonic microbial communities along a trophic gradient of central Adriatic Sea, regarding both biological and non-biological factors influencing the dynamics of microbial communities as ARGs carriers, and consequently, the diversity and distribution of ARGs on a seasonal and spatial scale. Combining culture-dependent and state-of-the-art culture-independent tools such as next-generation sequencing (NGS) we will assess spatial and temporal dynamics of marine microbiome composition along five sites in central Adriatic that differ by level of anthropogenic influence, physicochemical and biological factors. Seasonal and spatial changes in ARGs distribution will be quantified by RT-PCR. Multi-resistant isolates will be studied for the presence of other resistance determinants and genotyped for clonal relatedness. This, along with NGS sequencing of native plasmids carrying resistance traits will provide new insights on routes of ARGs exchange in environment, and further to taxonomically distant species of human pathogens. The research of diversity and mobility of environmental resistome is among crucial factors for the understanding of the overall epidemiology of antibiotic resistance spread and the ultimate success of its control, which is of global importance for the human and environmental health