Structural and functional diversity of biofilm bacterial communities along the Pearl River Estuary, South China

Abstract

Understanding the structural and functional patterns of bacterial communities in biofilm along environmental gradients is crucial in estuarine ecology. This study investigated bacterial community structural and functional diversity in intertidal biofilms along the Pearl River Estuary. We hypothesized that bacterial community in biofilm differs from its surrounding environments along salinity gradients, such as those in surface water and sediments. In this study, we collected 24 biofilm samples from eight sites along the Pearl River Estuary. We used 16S rRNA V4–V5regions amplicons-sequencing to characterize the bacterial communities. A total of 396,199 reads were assigned to 10,689 operational taxonomic units (OTUs). The Proteobacterial subphyla Alphaproteobacteria and Gammaproteobacteria were most prominent among all of the sampling sites, with bacterial diversity generally decreasing from fresh to saline along this estuary. Conductivity, total dissolved solids (TDS), and salinity were major drivers shifting the bacterial community composition in the intertidal biofilm in this estuary. Functional profiles involved in amino acid metabolism, carbohydrate metabolism, and membrane transport also were altered along this estuarine environment. We concluded that compositional and functional diversity of the bacterial communities in biofilm varies along the Pearl River Estuary. These results may provide a foundation for further studies of microbial communities in biofilms located in estuarine ecosystems.