Response to Environmental Perturbations in Microbial Nutrient Cycling Ecosystems

This thesis presents a combination of mathematical models and experimental data on the response of nutrient-cycling microbial ecosystems to changes in their nutrient environment. In particular: We use mathematical models to predict how simple models for nutrient-cycling populations respond to changes in the concentrations of electron acceptor and electron donor chemical species. We use experiments to test how a real microbial community responds to changes in the amounts of added carbon and sulfur, measuring both its chemical composition and its species composition via DNA extraction and sequencing. We use more complete chemical and thermodynamic models, implemented via Geochemists' Workbench, to predict the effects of abiotic reactions and microbial thermodynamics, on the response of microbial ecosystems to environmental change.