微塑料对土壤不同团聚体组分中微生物群落和功能基因的影响

EFFECTS OF MICROPLASTICS ON MICROBIAL COMMUNITIES AND FUNCTIONAL GENES IN SOIL WITH DIFFERENT AGGREGATE-FRACTION LEVELS

微塑料作为一种新型的环境污染物,对土壤生态系统构成了严重威胁。研究微塑料对土壤微生物及其功能的影响,对深入地认识塑料污染对陆地生态系统的危害具有十分重要的作用。基于土壤异质性理论,采用土壤物理分组方法和高通量测序技术,分析不同土壤团聚体组分中微塑料对土壤微生物及其功能的影响。结果表明:微塑料可显著提高放线菌门(Actinobacteria)和降低变形菌门(Proteobacteria)的相对丰度,从而改变微生物群落结构。微塑料处理组中放线菌门替代变形菌门成为优势菌门。3种团聚体组分中,微塑料处理组碳水化合物代谢、脂质代谢、外来生物生物降解和代谢、萜类和聚酮类的代谢和免疫性疾病功能途径的相对丰度均高于对照处理。3种团聚体组分中微塑料对细菌代谢功能的影响方向较为一致,但影响程度顺序为大团聚体组分(0.25~2 mm)>小团聚体组分(<0.053 mm)>微团聚体组分(0.053~0.25 mm)。3种土壤团聚体组分中,微塑料处理中参与不稳定C降解的特定基因、难降解C降解的基因、有机氮转化基因、反硝化基因、有机磷矿化、磷转运蛋白显著富集。研究结果表明:微塑料导致微生物群落结构以及功能发生变化,可能会改变土壤的生态功能。

As a new type of environmental pollutant,microplastics pose a serious threat to the soil ecosystem.Studying the effects of microplastics on soil microorganisms and their functions plays an important role in understanding the harm of microplastic pollution to terrestrial ecosystems.Based on the theory of soil heterogeneity,combining soil physical grouping methods and llumina Miseq high-throughput sequencing technology,this paper analyzed the effect of microplastics on soil microorganisms and their functions in soil with different aggregate-fraction levels.The results showed that microplastics altered the soil microbial community structure by significantly increasing and decreasing the abundance of Actinobacteria and Proteobacteria,respectively.Actinobacteria replaced Proteobacteria as the dominant phylum.Furthermore,the relative abundance levels of pathways related to carbohydrate metabolism,lipid metabolism,xenobiotics biodegradation and metabolism,metabolism of terpenoids and polyketides,and immune disease in microplastic treatments were higher than those in control treatments.The direction of effect of microplastics on bacterial metabolic function was consistent in three aggregate-size fractions,but the degree of effect decreased by the sequence of coarse particulate fraction(0.25 to 2 mm),non-aggregated silt and clay fraction(<0.053 mm)and micro-aggregate fraction(0.053 to 0.25 mm).Among three aggregate-size fractions,specific genes involved in labile-C degradation,recalcitrant-C degradation,organic N conversion,denitrification,and organic P mineralization were significantly enriched in microplastic treatments.The results showed that microplastic could change microbial community structure and function,which might change the ecological function of soil.