Microplastics increase int1 abundance and persistence of wastewater-derived microbes in freshwater

Plastic pollution is a major global concern with several million microplastic particles entering every day freshwater ecosystems via wastewater discharge, together with human pathogens. Microplastic particles stimulate biofilm formation (plastisphere) throughout the water column and have the potential to affect microbial community structure, especially enhancing the proliferation of biohazardous bacteria in pelagic systems. To test this scenario, we simulated the inflow of treated wastewater into a temperate lake using a continuous culture system with a gradient of concentration of microplastic particles. We followed the effect of microplastics on the microbial community structure by ARISA and on the occurrence of integrase 1 (int1, by qPCR), a marker associated to mobile genetic elements known as a proxy for anthropic effects on the spread of antimicrobial resistance genes.