Methane filtration and metabolic cooperation of microbial communities in cold seep water columns from South China Sea.

Microbes in cold seep water columns are essential for methane sequestration and biogeochemical cycling, yet their structures and ecological functions, particularly at the bottom water interface (BWI), are poorly understood. Here, we performed metagenomic analyses to explore the microbial biodiversity and functions at the F-site cold seep in the South China Sea. Functional stratification revealed that photosynthetic autotrophs dominate surface zones, heterotrophs are prevalent in mesopelagic zones, and chemosynthetic bacteria are abundant at the BWI. We obtained 377 metagenome-assembled-genomes (MAGs) and constructed genome-scale metabolic models to unveil metabolic interactions facilitating the coupling of carbon, nitrogen, and sulfur among microbes, particularly at the BWI. Notably, methanotrophic bacteria with diverse metabolic capabilities distributed from the BWI zone to the deep mesopelagic regions, highlighting the broader influence of methane. In conclusion, our findings reveal a high degree of heterogeneity in the composition and function of microorganisms across the F-site cold seep water column. Our study also sheds light on the ecological interactions and environmental gradients that shape these microbial communities.