Spatial dynamics of prokaryotic microbial communities in sediments of the Yellow Sea: Assembly process, co-occurrence relationships, and environmental implications

Marine sediment microorganisms play an important role in the biogeochemical cycle of elements and the transformation of exogenous pollutants; therefore, it is important to study the microbial assembly process and inter taxa associations. In this study, we investigated the profiles and assembly processes of microbial communities of sediments collected from 19 points in the Yellow Sea. As revealed by 16S rRNA sequencing, Proteobacteria (43.11%-65.54%) was the dominant phylum in marine sediment. Further, the physicochemical properties of sediments were significantly influenced by depth (P < 0.05), and the effects of homogeneous selection became greater with increasing depth. The microbial species located in marine sediment at 35 degrees N had a significantly higher co-occurrence relationship (82.76%) than those at 34 degrees N (57.99%) and 36 degrees N (54.07%). Additionally, the microbial community structure of the sediments changed significantly at the genus level with strong fluctuations in the physicochemical properties. By contrast, the carbon, nitrogen, and sulfur associated functional gene diversity and abundance showed no clear variation among different locations, indicating the probable functional redundancy and a potential functional gene pool of the microbes in marine sediments. This study could provide new insights into the composition of microorganisms in sediments in the Yellow Sea, the driving force of microbial diversity, the assembly process, the modes of species' co-occurrence, and their ecological functions.