Heavy metals influence on spread and persistance of antibiotic resistance genes in waters

While bacterial strains that are resistant to antibiotics and/or to heavy metals are commonly found in aquatic environments, the relationship between genic elements of resistance to heavy metals (HMR) and those to antibiotics (AR) within natural bacterial communities is still little understood. Furthermore, the distribution of these genes in the water column and in sediments is still poorly elucidated. The presence of antibiotic resistant bacteria and AR genes in aquatic environments in absence of a selective pressure is already documented, while the same assumption is not confirmed in respect to the resistance to heavy metals. Moreover, it remains unclear if native bacterial communities could adapt to heavy metals pollution by selection of HMR bacteria and if this adaptation could promote the AR spread by the co-selection between HMR and AR genes. With this research we aim to understand the vertical and the spatial distribution of HMR genes, their potential spread within the bacterial community, and their link to AR genes by improved quantitative PCR protocols. We will evaluate the impact of a previous heavy metal pollution on the bacterial community of restored Lake Orta (Italy) by sequencing analysis of 16SrDNA and correlation between composition and presence of resistance genes.