Microbes are central players in cycling of matter and energy on Earth and have been since the origin of life. Microbial cells, enzymes and reactive intermediates drive the biogeochemical cycles on our planet by supporting the establishment and persistence of chemical gradients, reaction networks and ecosystems. We work to understand the fundamental microbiological and environmental controls that drive Earths' biogeochemical cycles. Using observations from stable isotope geochemistry, biochemistry and microbial physiology we work to constrain fluxes and transformation rates within a subset of elemental cycles central to life on Earth (C, H, O, N, S, P).