Effect of phenol formaldehyde-associated microplastics on soil microbial community, assembly, and functioning

Increasing investigations explore the effects of plastic pollutants on bacterial communities, diversity, and functioning in various ecosystems. However, the impact of microplastics (MPs) on the eukaryotic community, microbial assemblages, and interactions is still limited. Here, we investigated bacterial and micro-eukaryotic communities and functioning in soils with different concentrations of phenol formaldehyde-associated MPs (PF-MPs), and revealed the factors, such as soil properties, microbial community assembly, and interactions between microbes, influencing them. Our results showed that a high concentration (1%) of PF-MPs decreased the microbial interactions and the contribution of deterministic processes to the community assembly of microbes, and consequently changed the communities of bacteria, but not eukaryotes. A significant and negative relationship was determined between N₂O emission rate and functional genes related to nitrification, indicating that the competitive interactions between functional microbes would affect the nitrogen cycling of soil ecosystem. We further found that vegetable biomass weakly decreased in treatments with a higher concentration of PF-MPs and positively related to the diversity of micro-eukaryotic communities and functional diversity of bacterial communities. These results suggest that a high concentration of the PF-MPs would influence crop growth by changing microbial communities, interactions, and eukaryotic and functional diversity. Our findings provide important evidence for agriculture management of phenol formaldehyde and suggest that we must consider their threats to microbial community compositions, diversity, and assemblage in soils due to the accumulation of PF-MPs widely used in the field.