Cells of Zymomonas mobilis immobilized in Ca-alginate matrix were used for ethanol production under various conditions.
Immobilized cells showed broad optimum pH profile and their operational optimum temperature shifted from 30℃ to 40℃ upon immobilization. As reportedly Z. mobilis did get the substrate inhibition by glucose, but at high concentration level of glucose the reduction of activity for ethanol production was less severe than that for yeast.
The used beads of the immobilized Z. mobilis were reactivated by incubation them in the activation medium. The increase in cell number and the enhancement of the specific activity per each cell are considered the two major factors responsible for the overall activation.
A packed-bed reactor with the feed glucose concentration of 20% （W/V）gave an ethanol productivity as high as 33.0 g/l.hr at the flow rate of 58.5 ml/hr.
A comparison between the experimental results from the real packed-bed reactor and the simulation results of an ideal case showed a two-fold inferior performance by the real reactor and this is at least partly attributed to the CO₂ gas effect.