(b) Saccharomyces cerevisiae,commonly known as baker’s or brewer’s yeast, is a unicellular fungus used for the commercial production of ethanol. It is a source of vitamin B and minerals and also used in the production of beer and wine. It is translated in the yeast and is useful for the production of ethanol. Ethanol is the clean fuel source of energy. It can be produced by fermentation of sugarcane, potato, sweet sorghum barley and corn, etc.