Abstract：
The impact of microplastics (MPs) as a new type of pollutant on water pollution has become a research hotspot. To explore the response relationship between the abundance of MPs and nitrogen metabolism function in a freshwater environment, Lake Ulansuhai was used as the research object; the abundance of MPs in the water was detected using a Zeiss microscope, and the distribution characteristics of nitrogen metabolism functional bacteria and functional genes in the water were analyzed using metagenomics sequencing. The correlation analysis method was used to explore the relationship between the abundance of MPs and nitrogen metabolism functional microorganisms and nitrogen metabolism functional genes. The results showed that the presence of MPs in freshwater environments had a higher impact on Cyanobacteria and Firmicutes as the dominant phyla, and the presence of MPs promoted their enrichment and growth. Among the dominant bacterial genera, MPs promoted the growth of Mycobacterium and inhibited Candidatus_Planktopila more significantly, further indicating that in freshwater environments, MPs affected normal nitrogen metabolism by affecting microbial communities, and pathways such as carbon and nitrogen fixation and denitrification were important pathways for MPs to affect nitrogen metabolism. From the perspective of nitrogen metabolism functional genes, it was found that the abundance of MPs significantly affected some functional genes during nitrification (pmoA-amoA, pmoB-amoB, and pmoC-amoC), denitrification (nirK and napA), and dissimilatory nitrate reduction (nrfA) processes (P < 0.05). Moreover, the influence of MPs abundance on different functional genes in the same pathway of nitrogen metabolism varied, making the impact of MPs on aquatic environments very complex; thus, its harm to the water environment cannot be underestimated.
摘要：
微塑料(MPs)作为一种新型污染物对水体污染的影响已成为研究热点。探讨淡水环境中MPs丰度与氮代谢功能的响应关系,以乌兰素海湖为研究对象,利用蔡司显微镜检测水中MPs的丰度,利用宏基因组学测序分析了水体中氮代谢功能菌和功能基因的分布特征。采用相关性分析方法探讨了MPs丰度与氮代谢功能微生物及氮代谢功能基因的关系。结果表明，MPs在淡水环境中的存在对蓝藻和Firmicutes作为优势门的影响更大。议员的存在促进了他们的丰富和成长。在优势细菌属中，MPs更显著地促进了分枝杆菌的生长，抑制了念珠菌的生长，进一步表明，在淡水环境中，MPs通过影响微生物群落影响正常的氮代谢，碳氮固定和反硝化等途径是MPs影响氮代谢的重要途径。从氮代谢功能基因的角度,结果发现，在硝化过程中，MPs的丰度显著影响了一些功能基因(pmoA-amoA，pmoB-amoB,和pmoC-amoC)，反硝化(nirK和napA)，和异化硝酸盐还原(nrfA)过程(P<0.05)。此外，MPs丰度对同一氮代谢途径中不同功能基因的影响不同,使国会议员对水生环境的影响非常复杂；因此，它对水环境的危害不可低估。
