城市红树林系统中微塑料表面细菌群落结构特征分析

以城市红树林生态系统为研究对象,研究该系统水体中微塑料表面细菌群落结构的多样性与组分特征。采用野外原位暴露实验的方法,利用扫描电镜显微镜（SEM）和16S rDNA高通量测序技术,检测聚乙烯（PE）、聚苯乙烯（PS）、聚氯乙烯（PVC）和具有可降解性的聚乳酸（PLA）4种不同类型微塑料表面形貌特征和细菌群落结构。结果表明：4种微塑料暴露45 d后（标记为LPE、LPS、LPVC、LPLA）在其表面均能观察到明显微生物聚集体,主要以杆状细菌、球状细菌为主;不同类型微塑料表面生物膜总量存在显著差异,表现为LPE>LPLA>LPS>LPVC;4种微塑料表面的细菌群落主要包括变形菌门（Proteobacteria）和拟杆菌门（Bacteroidetes）,而水环境中以蓝细菌门（Cyanobacteria_Chloroplast）、变形菌门（Proteobacteria）、放线菌门（Actinobacteria）和拟杆菌门（Bacteroidetes）为优势菌群。基于细菌群落多样性分析,结果发现微塑料表面生物膜中的细菌群落结构和周围水体存在显著差异,各个类型的微塑料表面细菌群落结构组分相似。红树林系统是微塑料的重要收纳场所,研究微塑料表面生物膜微生物群落特征,为进一步开展城市红树林系统中微塑料的环境行为与生态风险评价提供重要参考依据。

Microbial Colonization and Communities on Microplastics in Urban Mangrove System

Recently, microplastic pollution has become a new global environmental problem. Due to the strong hydrophobicity and large specific surface area, microplastics exposed to the environment can provide a new ecological site for microorganisms. Mangrove system is the “source” and “sink” of pollutants. Urban mangrove system was selected to study the diversity and composition characteristics of the bacterial community structure of the microplastics surface in the system. The method of in-situ exposure experiment, scanning electron microscope and 16S rDNA high-throughput sequencing technology were used to investigate the surface morphology characteristics and bacterial community structure of four types of microplastics (PE, PS, PVC, PLA). The results showed that obvious microbial aggregates were observed on the surfaces of the four microplastics after exposure (labeled as LPE, LPS, LPVC, LPLA), mainly bacilli and cocci (shape). There were significant differences in the total amount of biofilm on the surfaces of the four microplastics, which was represented by LPE>LPLA>LPS>LPVC. The results of high-throughput sequencing presented that the bacterial communities on the surfaces of the four microplastics mainly included Proteobacteria and Bacteroidetes. However, in the water environment, Cyanobacteria_Chloroplast, Proteobacteria, Actinobacteria and Bacteroidetes were the dominant flora. Based on the analysis of the diversity of the bacterial community, it was found that there were significant differences between the bacterial community structure in the microplastic surface biofilm and the surrounding water body, and the bacterial community structure composition on the surfaces of the four microplastics were similar. Since microplastics were accumulated in the mangrove area, it is necessary to study the microbial community characteristics of microplastic surface biofilm in order to provide an important reference for in-depth understanding the environmental behavior and ecological risk assessment of microplastics in urban mangrove systems.