Biogeography and diversity patterns of functional genes associated with C, N, P, S cycling processes across China classical sea sediments

Microbial activities influence the ecological functions of marine ecosystems and play an essential role in biogeochemical cycling. However, there are more studies on microbial diversity and community structure, and few reports have explored nutrient cycling processes by microbial functional gene abundance and diversity. Given these limitations, in order to investigate the variability of nutrient cycling among different sea areas and its influencing factors, the sediments of the Bohai Sea, Yellow Sea, East China Sea and South China Sea were used in this study. The number of average copies of each functional gene was obtained by the quantitative microbial element cycling (QMEC) smart chip. A total of 65 functional genes related to C, N, P and S cycling were identified, and the results showed that all functional genes decreased in the order of magnitude from the Bohai Sea to the East China Sea, Yellow Sea and South China Sea, and the abundance of functional genes was significantly higher at the sampling sites near the land side, which related to human activities. Additionally, NH4+, organic carbon, total carbon and geographical factor were the main driving factors of functional gene composition changes (p < 0.05), and all functional genes were significantly correlated with total carbon and geographical distance (p < 0.01). These findings further expand the understanding of marine ecosystems and provide robust support for global biogeochemical cycles.