Microplastics can alter microbial communities and enzymatic activities in soils. However, the influences of microplastics on soil carbon cycling which driven by microbial communities remain largely unknown. In this study, we investigated the effects of polyester microfiber (PMF) and natural organic matter（OM）on soil microbial communities, carbon-degraded enzymes, and carbon accumulation through an incubation experiment. Our results showed that the addition of PMF increased the activities of soil cellulase and laccase but did not impact soil bacterial and fungal communities too much. However, the addition of OM largely altered soil microbial communities and the activities of carbon-degraded enzymes, then mitigated the PMF effects on the activities of soil cellulase and laccase. On the other hand, greater alpha diversity of bacterial community attached on PMF was observed than those in the surrounding soils. The interaction of PMF and OM increased the richness of bacterial community in soils and on PMF. More importantly, we observed that the accumulation of natural organic carbon in soils reduced with increasing PMF. Thus, our results provide valuable insights into the effects of microplastics on soil organic carbon dynamics and microbial communities, and further work is required to clarify the biochemical processes at the surface of microplastics.

微塑料可以改变土壤中的微生物群落和酶活性。然而，由微生物群落驱动的微塑料对土壤碳循环的影响仍然未知。在这项研究中，我们通过孵育实验研究了聚酯微纤维（PMF）和天然有机物（OM）对土壤微生物群落，碳降解酶和碳积累的影响。我们的结果表明，添加PMF可以增加土壤纤维素酶和漆酶的活性，但不会对土壤细菌和真菌群落产生太大影响。然而，OM的加入大大改变了土壤微生物群落和碳降解酶的活性，从而减轻了PMF对土壤纤维素酶和漆酶活性的影响。另一方面，观察到附着在PMF上的细菌群落的α多样性比周围土壤更大。PMF和OM的相互作用增加了土壤和PMF上细菌群落的丰富度。更重要的是，我们观察到土壤中天然有机碳的积累随PMF的增加而减少。因此，我们的结果为了解微塑料对土壤有机碳动力学和微生物群落的影响提供了有价值的见解，还需要进一步的工作来阐明微塑料表面的生化过程。