oa Does Organic Matter Reflect Microbial Community Shifts in the Hyrothermal System of the Valley of Geysers?

Organic matter in hydrothermal systems reveals a wide range of sources and biogeochemical processes. The concentration and composition of dissolved organic matter (DOM) in hydrothermal fluids can be strongly affected by the contribution of subsurface organic matter and thermally altered sedimentary organic matter. Previous studies showed that pH correlates with the content of DOM and contribution from e.g., terrigenous sources. Sedimentary organic matter (SOM) in hydrothermal systems originates from both autochthonous and allochthonous sources, with notable impacts on microbial communities and biogeochemical cycles. However, the majority of the research on hydrothermal OM has focused on marine seafloor vent systems; much less information is available for continental hot springs. In this study, we try to correlate changes in the molecular composition of sedimentary organic matter (SOM) and dissolved organic matter (DOM) in different samples and sample types from the multi-habitat environment of the Valley of Geysers from Kamchatka peninsula with changes in their diverse bacterial and archaeal community using FT-ICR-MS.