Bioethanol and biobutanol production from sugarcorn juice

Corn hybrids with high stalk sugar content or 'sugarcorn', are fast-growing energy crops recently developed by Agriculture and Agri-Food Canada. For the first time, this study uses juice extracted from sugarcorn plants for bioethanol and biobutanol production via microbial fermentation. Characterization results for sugarcorn juice from two different crop harvest times are presented. Juice characteristics such as, moisture content, total solids, total dissolved solids, pH, density, elemental analysis, protein, reducing sugars and total carbohydrates were determined for the two juice batches. Sugarcorn juice used in the study contained a maximum of 145 g L−1 carbohydrates, with sucrose, glucose and fructose accounting for 80% of the sugars. Saccharomyces cerevisiae grown in sugarcorn juice supplemented with 3 g L−1 yeast extract produced 45.6 g L−1 ethanol in 72 h of fermentation (yield = 0.41 g ethanol per g carbohydrates). For biobutanol fermentation, a sporogenic strain of Clostridium beijerinckii was cultivated anaerobically in sugarcorn juice-P2 medium, achieving a butanol concentration of 8.3 g L−1 in 257 h (yield = 0.31 g butanol per g total fermentable sugars). Sugarcorn is a new Canadian energy crop and a source of readily fermentable sugars, that has the potential to save on energy and enzyme costs, when compared to corn grain based biofuel production processes.