Micro-nanoplastics enhance viral survival and infectivity: Experimental evidence from a bacteriophage D1 model system

Micro- and nanoplastics (MNPs), ubiquitous pollutants in aquatic environments, can interact with waterborne viruses. However, their combined effects remain poorly understood. This study aimed to elucidate how MNPs affect viral infectivity and persistence under varying physicochemical and environmental conditions. Using the self-isolated bacteriophage D1 as a viral model, we investigated how different types, sizes, and concentrations of MNPs influence infection of the host bacterium JS682. Results demonstrated that MPs significantly enhanced viral infectivity, with the effect being positively correlated with MNP concentration, particle size, and degree of aging. Compared to control, MNPs in lake water further promoted viral infection, whereas seawater exhibited an inhibitory effect. After two weeks of incubation, phages exposed to MNPs showed a 44.5 % higher survival rate than the control group, indicating that MNPs can prolong phage viability. Mechanistic investigations using reverse transcription quantitative PCR and Fourier-transform infrared spectroscopy confirmed that MNPs facilitate viral infection through adsorption processes. These findings suggest that MNPs can act synergistically with viruses in aquatic environments, posing potential ecological risks and highlighting the need for comprehensive risk assessments in water pollution management.