Contrasting bacterial diversity, community composition, and metabolic function of the sediment between two different regions in lake Chaohu, China

Lake Chaohu, the fifth-largest freshwater lake in China, has been experiencing severe eutrophication and algal bloom problems. Owing to differences in trophic status, the lake is divided into two distinct regions. However, the sediment bacterial communities within the lake remain poorly understood. This study aims to fill this knowledge gap by comparing sediment bacterial communities between the two different lake regions using 16S rRNA gene amplicon sequencing. A total of 1,222,845 high-quality sequences were generated, encompassing 92 phyla and 3296 genera across 20 surface sediment samples. The results indicated that the pH, loss on ignition (LOI), and the total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) concentration of sediments in the western region were significantly higher than those in the eastern region. Furthermore, bacterial α-diversity, β-diversity, and community composition in the sediments exhibited marked differences between the two lake regions. The functional profiles of the bacterial populations also revealed statistically significant differences in predicted functional composition among the two different lake regions. Redundancy analysis (RDA) identified that TN, TP, and TOC are the primary factors influencing the variations of sediment bacterial communities between the two different lake regions. Overall, this study substantially advances our understanding of sediment microbial ecology in eutrophic freshwater lakes.