Bioprospecting Starchy Feedstocks for Bioethanol Production: A Future Perspective

Ethanol is one of the main bio-based molecule produced worldwide, mainly from corn and other starchy crops. Starchy substrates employed as raw materials for ethanol production which cannot be directly fermented to ethanol by certain microorganisms. This is because yeasts, which are employed for fermentation, cannot utilize the starch molecules made up of long chains of glucose molecules hence prior to fermentation need to hydrolyze to simpler fermentable sugars into simple glucose molecules. Although corn starch to ethanol is a mature process, corn production is not feasible in different region. Except corn starch, there are some low impact tuber crops including cassava, sweet potato, yam, aroids, sugar beet, etc. which offer a viable alternative starchy raw material that can be converted to useful sugar feed stocks needed for the production of ethanol and other value added products. It requires simultaneous saccharification and fermentation for a better ethanol yield. Production of this renewable fuel, especially from starchy materials such as tuber crops, holds a remarkable potential to meet the future energy demand because of its high production and comparatively less demand for use as food and fodder. Thus, the present review focuses on various starchy crops for bioethanol production, fermentation techniques and microorganisms used in fermentation process along with its future prospective.