This work presents the development of an unstructured kinetic model incorporating the differing degrees of product inhibition on the kinetic rates of recombinant Zymomonas mobilis fermentation. A mechanism for the inhibition of two competing substrates cellular uptake via membrane transport is proposed. The model was utilized in a nonlinear model predictive control (NMPC) algorithm to control product concentration during fed-batch fermentation. Using optimal feeding policy determined online by the NMPC controller, the volumetric productivity of ethanol was improved by 16.6 percent relative to the equivalent batch operation when the same final ethanol concentration was reached.