Novel Process with Advantages over Yeast Fermentations: The Zymomonas Process for Fermentation Ethanol

Bacterial ethanol fermentations using strains of Zymomonas mobilis are shown to offer many advantages over traditional yeast fermentations. These include significantly higher specific rates of sugar uptake and ethanol production and improved yields. In a continuous cell recycle system, a volumetric ethanol productivity of 120/g/l/h is reported. Studies on a new strain of Z.mobilis isolated from fermenting sugar cane juice have shown improved rates of glucose uptake and ethanol production and an enhanced tolerance to ethanol. Possible future developments such as optimal cell recycle and the application of genetic techniques to the problems of improving ethanol tolerance and broadening the range of substrates utilized by Zymomonas are discussed.