Location: Bioenergy ResearchTitle: Use of tropical maize for bioethanol production Author
Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2013
Publication Date: 3/19/2013
Citation: Chen, M.-H., Kaur, P., Dien, B.S., Below, F., Vincent, M.L., Singh, V. 2013. Use of tropical maize for bioethanol production. World Journal of Microbiology and Biotechnology. 29:1509-1515. Interpretive Summary: Grain corn is the major feedstock for production of fuel ethanol in the United States. Tropical corn can serve as an alternate crop that requires only 50% of the nitrogen fertilizer compared to grain corn. The hybrid used in this study has been adapted for production in the Midwest. Unlike with grain corn, sugars are accumulated in the stalks as syrup. In this study, tropical maize was harvested; the sugars pressed out, concentrated, and fermented using yeast. The highest ethanol concentration (15.6%v/v) is comparable to what is expected in corn ethanol fermentations. However, the fermentation rate was slower than expected and further research is warranted to solve this issue.
Technical Abstract: Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25 - 2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1% (v/v) to 15.6% (v/v), equivalent to 90.3 - 92.2% of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry.