Mechanisms of polyethylene microplastics on microbial community assembly and carbon-nitrogen transformation potentials in soils with different textures

Pollution caused by microplastics (MPs) is progressively altering soil health worldwide, with far-reaching consequences that may adversely affect ecosystems and public well-being. Using high-throughput sequencing of 16S rRNA, this research explores the impact of polyethylene (PE) MPs on the diversity and function of soil microbial communities, focusing on how these particles affect the movement of carbon and nitrogen across soils with different textures. The research analyzed soil samples of three different textures from 14 different regions. Results show that PE MPs reduced microbial richness in sand and clay soils by 17.33 % and 15.24 %, respectively, but increased richness in loam soils by 62.34 % (P < 0.01), mainly promoting the proliferation of bacteria such as Sphingomonas. Clay-plastic-associated soils exhibited 69,789 microbial network edges, significantly higher than sand (28,286) and loam (37,044), indicating enhanced functional connectivity, with more functionally important microorganisms present. Further analysis shows that the carbon sequestration capacity and nitrogen-transforming activity of plastic-associated soils increased with decreasing soil particle size. The structure and ecological balance of microbial populations linked to plastics in clay soils were predominantly governed by the organic matter present in the soil and the proportion of the C/N ratio. These results provide new insights into the effects of MPs on soil ecosystems and theoretical support for MPs pollution management and ecological restoration.