Ethanol, which is a type of alcohol, is one of the most popular biofuels. It can be made out of feedstocks such as corn, barley and sugarcane through a chemical process known as ethanol fermentation. Any sugars such as glucose, fructose and sucrose that be converted into cellular energy can produce ethanol. Yeast performs the conversion in the absence of oxygen, which means ethanol fermentation is anaerobic.
Fermentation is one of the oldest chemical processes that humans became familiarized with. It can be used to make fuels, several types of food, flavoring, beverages, pharmaceuticals, and chemicals. Fermentation of any material that contains sugar or compounds that can be converted to sugar can produce ethanol. There are three types of raw materials that can be used to make ethanol via fermentation. These are sugars (sugar cane, molasses sugar beets); starches (includes grains, root crops, potatoes, which need to be hydrolyzed to fermentable sugars by enzymes from malt or moulds); and cellulose (includes agricultural residues, wood, or waste sulfite liquor from pulp and paper mills). Cellulose must also be converted to sugars through the action of enzymes. Once simple sugars are formed, yeast enzymes can easily ferment them to ethanol.
There is constant research on the process of ethanol fermentation as part of a search for more efficient fermentative organisms. These could help reduce costs and obtain better environmental conditions in which fermentation could occur.
Zymomonas mobilis is one type of bacterium that shows potential as a replacement for yeast in big-scale fuel ethanol production. Scientific studies have found that this bacterium presented an increased sugar uptake and ethanol yield, besides other technical advantages.