community_experiment_and_pure_culture.xlsx

Viruses represent the most abundant biological entities on Earth and may play crucial roles in structuring microbial communities and biogeochemical cycles. A number of environmental factors may affect viruses and their microbial hosts differentiate. Here we report two experiments that addressed the impacts of microplastics (MP) on viruses and bacteria in soils. In a pure culture experiment, soil microcosms in test tubes with only bacterium <i>Pseudomonas fluorescens</i> SBW25, or bacteriophage SBW25Φ2, were exposed polyethylene (PE) or polyvinyl chloride (PVC) pollution. In a microbial community experiment, soils with natural microbes in pots planted with maize were given PE or PVC contamination with a gradient of dosage. In both experiments, PE and PVC significantly reduced viral abundances. However, their effects on bacterial abundances were context-dependent. Bacterial growth in pure culture soil microcosms was unaffected by MP exposure. In the microbial community experiment, high-dose PE increased bacterial abundance and decreased the virus-to-bacteria ratio (VBR). High-dose PVC markedly reduced bacterial abundance without substantially altering VBR.