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Ethanol Production from Pearl Millet Using Saccharomyces cerevisiae¹

¹Contribution No. 05-297-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66506. ²Department of Biological and Agricultural Engineering, Kansas State University, Manhattan, KS 66506. ³Corresponding author. Phone: 785-532-2919. Fax: 785-532-5825. E-mail: dwang@ksu.edu ⁴USDA-ARS Grain Marketing and Production Research Center, Manhattan, KS 66502. ⁵USDA-ARS Crop Genetics & Breeding Research Unit, Tifton, GA 31793-0748.

Four pearl millet genotypes were tested for their potential as raw material for fuel ethanol production in this study. Ethanol fermentation was performed both in flasks on a rotary shaker and in a 5-L bioreactor using Saccharomyces cerevisiae (ATCC 24860). For rotary-shaker fermentation, the final ethanol yields were 8.7–16.8% (v/v) at dry mass concentrations of 20–35%, and the ethanol fermentation efficiencies were 90.0–95.6%. Ethanol fermentation efficiency at 30% dry mass on a 5-L bioreactor reached 94.2%, which was greater than that from fermentation in the rotary shaker (92.9%). Results showed that the fermentation efficiencies of pearl millets, on a starch basis, were comparable to those of corn and grain sorghum. Because pearl millets have greater protein and lipid contents, distillers dried grains with solubles (DDGS) from pearl millets also had greater protein content and energy levels than did DDGS from corn and grain sorghum. Therefore, pearl millets could be a potential feedstock for fuel ethanol production in areas too dry to grow corn and grain sorghum.