Since during
ethanol fermentation, the microorganisms are usually under resting-
cell conditions with very little cell growth, using immobilized
cells has a particular advantage of being able to retain the cells
in the system during continuous operations. Therefore, although
suspended-cell system is still the dominant way for bioethanol fermentation,
there are still many reports describing the use of immobilized
cells (especially for immobilized S. cerevisiae) for bioethanol
production [13,15,16].