Starch offers a high-yielding ethanol production resource, and several starchy substrates such as corn, grain, potato, rice have been used for ethanol production. While the most efficient and the traditionally used fermenter of glucose to ethanol lacks the amylolytic activity to utilize starch directly. The conventional ethanol production has been a two-step process that requires the initial degradation of starch to fermentable sugars, at least to maltotriose, the longest glucose polymer that can be metabolized by using yeast cell. The ever increasing demand for the production of alcohol as a fuel additive has boosted the use of amylolytic yeasts indirect utilization of the starch-rich crops like grain, wheat and corn and industrial wastes to formulate more economical and simplified the single-step process for ethanol production. This whole ethanol production using crops by used glucoamylase for grain.
