In this research area, we investigate biotic and abiotic processes controlling organic matter evolution, transport and degradation in the subsurface. Sediments and sedimentary rocks at great depth have joined the growing list of localities where microbial life exists under extreme conditions. The as yet mostly unexplored "Deep Biosphere" plays a fundamental role in the global biogeochemical cycles. Using high resolution analytical methods we demonstrate the existence of microbial communities using biogeochemical and geomicrobiological methods, including so-called “life markers”. The information hidden in high molecular weight polar compounds can now be unraveled and used to characterise their geosynthesis and transformation, providing new insights into the controls on e.g. petroleum physical properties. The role of water as reactant and transport media for organic components in the subsurface is characterised using isotopic analysis as well as ultra-high resolution molecular methods. Applications range from elucidating petroleum water partition processes to the mobility of organic matter in geo-engineering systems. We analyse fluid inclusion to decipher paleo-events and predict subsurface rock and fluid properties. Additionally we model metabolic processes in the geosphere and in biogenic natural gas formation.