I am a geobiologist. I am driven to understand how microbial metabolisms shape global biogeochemical cycles through time. I view the co-evolution of the geosphere and the biosphere – more specifically that of sedimentary environments and microbial communities – as a composite of three components: environmental conditions, microbial physiology, and enzyme kinetics. I strive to understand the nature of this co-evolution over time and quantify the relative contributions of these components to geochemical records and global biogeochemical cycles. I apply sophisticated microbial isotope models that incorporate enzyme isotope effects modulated by physiology and environment. I calibrate these with molecular-level models, in vitro enzyme work, microbial experiments, environmental observables, and geochemical records.
So far, I have focused on microbial metabolisms that drive cycles essential to the establishment of Earth surface conditions: (1) microbial sulfate reduction (MSR) and microbial sulfur disproportionation (MSD), which are both central to the sulfur (S) cycle and couple S to carbon cycling and organic carbon burial, and (2) biological nitrogen fixation (BNF), which is essential to the nitrogen (N) cycle and is a crucial ecological innovation in Earth history.
Email: ebertran [at] princeton [dot] edu
Current mailing address:
Department of Geosciences,
Guyot Hall, Princeton University
Princeton, NJ 08544