Microplastics induced the differential responses of microbial-driven soil carbon and nitrogen cycles under warming.

The input of microplastics (MPs) and warming interfere with soil carbon (C) or nitrogen (N) cycles. Although the effects of warming and/or MPs on the cycles have been well studied, the biological coupling of microbial-driven cycles was neglected. Here, the synergistic changes of the cycles were investigated using batch incubation experiments. As results, the influences of MPs were not significant at 15, 20, and 25 °C, and yet, high temperature (i.e., 30 °C) reduced the respiration of high-concentration MPs-amended soil by 9.80%, and increased dissolved organic carbon (DOC) by 14.74%. In contrast, high temperature did not change the effect of MPs on N. The decrease of microbial biomass carbon (MBC) and the constant of microbial biomass nitrogen (MBN) indicated that microbial N utilization was enhanced, which might be attributed to the enrichments of adapted populations, such as Conexibacter, Acidothermus, and Acidibacter. These observations revealed that high temperature and MPs drove the differential response of soil C and N cycles. Additionally, the transcriptomic provided genomic evidence of the response. In summary, the high temperature was a prerequisite for the MPs-driven response, which underscored new ecological risks of MPs under global warming and emphasized the need for carbon emission reduction and better plastic product regulation.