The Environmental Simulation and Modeling campaign (EnvSim) has strategically aligned efforts across ENIGMA to investigate to ecologically important phenomena observed at the Oak Ridge Field Research Center (FRC). For example, field observations indicated that sulfate respiration and nitrate respiration processes operate in mutual exclusivity down the transect of a sediment core. Using the field isolate (Intrasporangium calvum C5) this phenomenon was simulated and the mechanistic underpinnings delineated through laboratory investigations.
Insights from this study are currently being tested back at the FRC using groundwater chemostats to demonstrate the “field-to-lab-to-field” iteration model employed across ENIGMA for investigating a phenomenon that emerged through the investigations of complex interactions within a microbial community. Another set of hypotheses being tested by the EnvSim campaign involve the interplay of biotic and abiotic factors that lead to N 2 O emissions at the FRC. It has been shown that in FRC wells which have a lower pH (~6.5 – 3) tend to have higher concentrations of N 2 O. The EnvSim campaign has deduced four potential mechanisms that may account for the N 2 O emissions at the FRC and are currently being investigated by labs across ENIGMA. We use different reactor systems to answer distinct questions, which provides important information and data that can be directed into our predictive models. For instance, we are using sophisticated column reactors and highly controlled, constantly stirred, planktonic reactors to study how microbial community structure and function changes in response to pH shifts, oxygen concentrations, and sulfurous compounds. Batch culture experiments are being used to study the abiotic and biotic impacts of metals on denitrification processes. In addition, transcriptomic analysis of these experiments are aiding the construction of a metabolic and gene regulatory network model. Importantly, the work being conducted by the EnvSim campaign illustrates the field-to-lab and lab-to-field framework of the ENIGMA campaign strategy.