Abstract
Zymomonas mobilis is a bacterium which presents several advantages over yeast with respect to ethanol production. It ferments monosaccarides with higher yields and tolerates higher concentrations of ethanol and sugars. However, the alcoholic fermentation of sucrose, which is the most widely used sugar for alcohol production in the Caribbean area, is poor. Therefore, it is important to find how to increase ethanol yield by using Zymomonas mobilis with sucrose as starting material. Our experimental results demonstrated that the addition of monosaccharides to a basic medium containing 6% sucrose increased ethanol yield by at least 10%. The addition of 2% fructose at the beginning of the fermentation period increased ethanol yield from 87.4% to 100%, whereas the addition of 2% glucose produced a yield of 97.5%. When 1% of both monosaccharides was added the final yield was 99.8%.