施氮对农用地膜表面微生物群落特征的影响

Responses of Microbial Community on Plastic Mulch Surface to Nitrogen Fertilization

【目的】农用地膜表面是塑料降解菌筛选、动植物病原菌定殖及抗生素抗性基因富集的潜在热点区域,但地膜表面招募微生物的群落基本特征仍不明确,一定程度上限制了我们对地膜表面微生物定殖过程的理解。【方法】本研究基于地膜覆盖和施氮长期定位试验,2021年秋季采集覆膜当季的地膜样品,利用高通量测序分析了地膜表面的细菌与真菌群落特征。【结果】地膜表面细菌以蓝细菌门(Cyanobacteria)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)为主,而真菌以座囊菌纲(Dothideomycetes)为主。地膜及土壤表面均产生肉眼可见的绿色絮状微生物菌落,这说明了覆膜对地表微气候的改善有利于地衣系统的发育。施氮间接提高微生物群落α多样性,但不改变β多样性。同时,与对照相比,施氮增加了地膜表面细菌中芽单胞菌门(Gemmatimonadetes)相对丰度约160%,并分别提高了真菌中银耳纲(Tremellomycetes)和囊担菌纲(Eurotiomycetes)的相对丰度4.8倍和3.9倍。此外,地膜表面的细菌群落比真菌群落对施氮的响应更敏感。【结论】地膜表面是微生物的一个独特生境,施氮可间接影响地膜表面的微生物群落特征。

【Objective】The surface of plastic film is a potential hotpot zone for screening of plastic degrading bacteria,colonization of animal and plant pathogens and enrichment of antibiotic resistance genes.However,the basic characteristics of microbial community on the surface of plastic film are still unclear,which limits our understanding of the microbial colonization of plastic film mulching system to some extent.【Method】Based on the long-term positioning experiment of plastic film mulching maize and nitrogen fertilization,we analyzed the characteristics of bacterial and fungal communities on the surface of plastic film in autumn 2021 under urea fertilization and no urea fertilization by high-throughput sequencing.【Result】Microbial bacteria on the plastic films were mainly dominated by Cyanobacteria,Proteobacteria and Actinobacteria,while fungi were dominated by Dothideomycetes.Green flocculent microbial colonies were observed on the surfaces of plastic film and soil,which reflected the improvement of surface microclimate by film mulching was beneficial to the development of lichen system.Nitrogen application inclirectly in creased theα-diversity of microbial communities,but did not alter β-diversity.Meanwhile,compared with the non-fertilized plot,the relative abundance of Gemmatimonadetes in bacteria increased by 160% at urea fertilization plot;the relative abundance of Tremellomycetes and Eurotiomycetes in fungi increased by 4.8 and 3.9 times,respectively.In addition,bacterial community is more sensitive on the film surface compared with the control under nitrogen fertilization.【Conclusion】Plastic film surface is a unique habitat for cropland soil microorganisms,and nitrogen fertilization can have an indirect impact on characteristics of microbial community surface of agricultural plastic film.