Microplastics of Broad Size Range Reduce Bacteriophage Activity in Aqueous Environments

Microplastics, pervasive environmental contaminants, attract significant attention due to their detrimental effects across ecosystems. Reports show the presence of microplastics in water, soil, aqueous organisms, and even human tissues and blood. This study investigates the impact of microplastics on bacteriophages, i.e., viruses that play crucial roles in regulating microbial communities and maintaining ecological balance. Since bacteriophages lyse up to 40% of bacterial populations daily, their role in environmental stability is paramount. We demonstrate that microplastics can reduce the apparent number of active bacteria in aquatic environments. To explore the interaction between microplastics and bacteriophages, we examine the effects of various microplastic types (polystyrene, poly(vinyl chloride), polyethylene, and polyethylene terephthalate) and size ranges of particles on phages of varying morphologies (tailed T4, filamentous M13, and icosahedral MS2). Additionally, we assess the influence of bacterial debris, representing organic matter, on the heteroaggregation of microplastic particles and phages. Our findings reveal a significant decline of up to 99.99% in active phages, underscoring the profound effects of microplastics on phage dynamics. These results provide critical insights into the complex interactions between microplastics and phages, highlighting the need for urgent action to address microplastic pollution.