High productivity continuous ethanol fermentations

In the current research program, continuous culture systems with cell recycle are being evaluated for ethanol production. The successful development of such a system could lead to a significant reduction in fermentation costs. Bacterial ethanol fermentations using strains of zymomonas mobilis have been found to offer many advantages over the traditional yeast fermentations. These include higher specific rates of sugar uptake and ethanol production and improved yields. In a continuous process with cell recycle ethanol productivities have been achieved with the bacterial cultures which are several times higher than those reported for yeasts (a).