(191bj) Efficient Energy Utilization in Carbon-Fixing Moorella Thermoacetica

Authors: 
Park, J. O., Massachusetts Institute of Technology
Liu, N., Massachusetts Institute of Technology
Stephanopoulos, G., Massachusetts Institute of Technology
Carbon dioxide is the main greenhouse gas that is produced in combustion and cellular respiration. On the other side of the carbon cycle, plants and algae reduce CO2 using photosynthesis. Despite technological advances, industrial society emits CO2 faster than the rate at which it can be eliminated, breaking balance in the carbon cycle. Metabolic CO2 reduction requires energy in two forms: reducing power and ATP. Here we find that when glucose is the sole energy source, non-photosynthetic carbon-fixing anaerobe Moorella thermoacetica is limited by reducing power. Despite electron-limitation, we observe near-complete carbon utilization for acetate and biomass production. Using 13C glucose and 12CO2, we observe that CO2 accounts for most carbons of non-aromatic amino acids and secreted acetate. In this talk, we will introduce and apply simultaneous 13C and 18O tracing to identify energy-efficient pathways that allow cells to proliferate in chronically nutrient- and energy-limited environments. Identification of metabolic limitations using similar isotope tracer strategies should be broadly useful for improving bioprocesses.