Comparison of Bioethanol Production by and from Glucose, Cellobiose, and Cellulose.

Bioethanol has attracted much attention in recent decades as a sustainable and environmentally friendly alternative energy source. In this study, we compared the production of bioethanol by and at different initial concentrations of cellobiose and glucose. The results showed that can utilize both glucose and cellobiose, whereas can only utilize glucose. The ethanol yields were 43-51% from different initial concentrations of carbon source. In addition, different concentrations of microcrystalline cellulose (Avicel) were directly converted to ethanol by a combination of and two yeasts. Cellulose was first hydrolyzed by a fully enzymatic saccharification process using cellulases, and the reducing sugars and glucose produced during the process were further used as carbon source for bioethanol production by or . Sequential culture of and two yeasts revealed that was more efficient for bioconversion of sugars to ethanol than . When 20 g/l Avicel was used as a carbon source, the maximum reducing sugar, glucose, and ethanol yields were 42%, 26%, and 20%, respectively. The maximum concentrations of reducing sugar, glucose, and ethanol were 10.9, 8.57, and 5.95 g/l, respectively, at 120 h by the combination of and from 50 g/l Avicel.