Subduction zones link shallow and deep biogeochemical processes, as fluids and volatiles are transferred between the two converging plates and the mantle. The resulting heterogeneous hydrothermal system associated with the subduction-related volcanisms offers a range of possible environments for life. Environmental microbes are often linked to the chemical processes they catalyze, however, few studies have determined how microbial distribution reflects deep subsurface processes on the scale of an entire subduction zone. Additionally, the possible role of subsurface microbial communities in influencing the volatile budget is not clear. Here, I will present our latest work and unpublished data regarding the role of subsurface microbial communities in modifying volatile cycling across subduction zones, and how deep plate processes can influence near-surface microbial life creating a complex system of feedback loops between the geosphere and biosphere.