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

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.

Key words:Poyang Lake;microplastics;wet season;dry season;bacterial distribution