(589g) Continuous Production of Ethanol in High Productivity Bioreactors Using Escherichia Coli Fbr5: Membrane and Fixed Cell Reactors

Biochemical reactor design plays a major role in determining the economics of fuel and chemical production. Reactors that result in continuously high productivities can significantly reduce the cost of the final product. With this aim, three different continuous reactor systems were evaluated for ethanol production from xylose using E. coli FBR5, a strain engineered to produce ethanol in high yield from xylose. The reactor systems evaluated were adsorbed cell, entrapped cell, and membrane cell recycle bioreactors. The cell concentration inside the adsorbed cell reactor varied with time from 0.17-70.2 g/L reactor volume. The entrapped cell reactor contained 39.3 g cell/L bead volume. The cell slurry that was used to fix the cells contained 59.0 g cell/L slurry (dry weight). In the entrapped cell reactor, a maximum ethanol concentration of 37.1 g/L was obtained at a dilution rate of 0.022 h^-1. In this reactor, a productivity of 2.0 g/L.h was obtained at a dilution rate of 0.08 h^-1. At this dilution rate, the ethanol concentration in the effluent was 25.1 g/L. Membrane cell recycle reactors offer high productivities; however, they are fouled by the medium components. All three of the reactors evaluated resulted in productivities higher than batch reactors.