Vertical distribution characteristics and influencing factors of bacterial communities in a sediment profile of Bohai Sea.

Research on the diversity of bacterial communities and their influencing factors in the sediments of the Bohai Sea remains limited. This study used high-throughput sequencing technology to explore the vertical distribution characteristics and influencing factors (depth, heavy metals, and nutrients) of bacterial communities in sediment core B18 from the Bohai Sea. Our results indicated that the dominant phyla were Proteobacteria, Desulfobacterota, Acidobacteriota, Chloroflexi, Bacteroidota, and Actinobacteriota, with Alphaproteobacteria, Gammaproteobacteria, Bacteroidia, Anaerolineae, Thermoanaerobaculia, and Desulfobulbia as the dominant classes. Depth exerted a pronounced influence on bacterial community diversities, with bacterial communities (excluding Proteobacteria, Bacteroidota, and Verrucomicrobiota) displaying a positive correlation with depth. Anaerobic bacteria like Desulfobacterota and Chloroflexi were more prevalent in the deeper sediment layers. In contrast, most bacterial communities exhibited a negative relationship with heavy metal concentrations. Notably, As, Pb, and Cd contents exhibited relatively high levels of pollution and had a considerably negative effect on bacterial diversity. Bacterial communities with adaptability to heavy metals (such as Proteobacteria, Bacteroidota, Verrucomicrobiota) demonstrated a competitive advantage in the Bohai Sea sediment bacterial community compositions. Meanwhile, bacterial communities related to nitrogen, phosphorus, and sulfur cycling (Proteobacteria, Bacteroidota, Verrucomicrobiota) were relatively abundant. This study offers valuable insights into the diversity and compositions of bacterial communities in the Bohai Sea sediment profile by elucidating the vertical distribution and influencing factors of sediment bacterial communities.