Hydrogen production envelopes as a function of the biomass production rate of the wild-type E. coli network under aerobic and anaerobic conditions as well as the two-reaction and three-reaction deletion mutant networks. The basis glucose uptake rate is fixed at 10 mmol/gDW per hour. These curves are constructed by finding the maximum and minimum hydrogen production rates at different rates of biomass formation. Point A denotes the required theoretical hydrogen production rate at the maximum biomass formation rate of the wild-type network under anaerobic conditions. Points B and C identify the theoretical hydrogen production rates at maximum growth for the two mutant networks, respectively, after fixing the corresponding carbon dioxide transport rates at the values suggested by OptKnock.