鄱阳湖湿地不同水期微塑料表面细菌群落分布特征

Distribution characteristics of bacterial communities on microplastic surface in wet and dry seasons in Poyang Lake wetland

摘要:

【目的】 微塑料(粒径<5 mm)具有疏水表面、吸附能力强、难降解等特征，可长期留存于环境中，并且易被微生物所定殖，对生态系统存有潜在风险。本研究以鄱阳湖湿地微塑料表面微生物为研究对象，探究不同水期微塑料表面细菌群落结构分布特征。【方法】 分别在丰水期和枯水期采集湿地水体、沉积物及沉积物中微塑料样品。借助16S rRNA基因高通量测序技术，对样品的细菌多样性及群落结构展开分析。【结果】 不同水期环境中的细菌丰富度和多样性皆高于微塑料表面。丰水期水体和沉积物细菌群落结构相似，环境与微塑料表面细菌结构差别较大，枯水期水体和沉积物以及微塑料表面细菌群落结构差别均较大。环境样品中的细菌门水平上以变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和放线菌门(Actinobacteria)为主，而丰水期微塑料表面细菌群落主要包括变形菌门、拟杆菌门、厚壁菌门(Firmicutes)，枯水期微塑料表面细菌群落与环境中相似。微塑料表面细菌群落中假单胞菌属(Pseudomonas)相对丰度比环境中高。丰水期和枯水期细菌群的关键种中大部分属于变形菌门，包括鞘氨醇单胞属(Sphingomonas)等。【结论】 本研究揭示了鄱阳湖湿地不同水期环境中以及微塑料表面细菌群落结构差异，研究可以丰富和完善我国湖泊湿地中微塑料的相关知识，为湖泊环境治理与管控提供理论支持与依据，以便对鄱阳湖湿地进行生态系统管理。

Abstract:

[Objective] Microplastics (particle size<5 mm) with hydrophobic surface, strong adsorption capacity, and difficult degradation can be retained in the environment for a long time and easily colonized by microorganisms, which poses a potential risk to the ecosystem. To study the distribution characteristics of microorganisms on the surface of microplastics in the wetland of Poyang Lake in wet and dry seasons. [Methods] Samples of water, sediments, and microplastics in sediments were collected from the wetland during the wet and dry seasons. The bacterial diversity and community structure in the samples were analyzed by high-throughput sequencing of the 16S rRNA gene. [Results] The richness and diversity of bacteria in the environment were higher than those on the microplastic surface in wet and dry seasons. During the wet season, the bacterial community structure was similar between the water and sediment samples and had large differences between the environment and the microplastic surface. During the dry season, the bacterial community structure was different among different samples. At the phylum level, the bacteria in the environment were dominated by Proteobacteria, Bacteroidetes, and Actinobacteria, while the bacteria on the microplastic surface during the wet season mainly included Proteobacteria, Bacteroidetes, and Firmicutes. The dominant bacterial phyla on the microplastic surface were similar to those in the environment during the dry season. The relative abundance of Pseudomonas on the microplastic surface was higher than that in the environment. Most of the keystone bacterial species in the wet and dry seasons belonged to Proteobacteria, including Sphingomonas. [Conclusion] This study reveals the differences in the bacterial community structure in the environment and on the microplastic surface in the Poyang Lake wetland in wet and dry seasons. The findings can enrich the knowledge about microplastics in lake wetlands in China and provide a theoretical basis for the management of lake environments including the Poyang Lake wetland.