Evaluation of oxygen availability on ethanol production from sugarcane bagasse hydrolysate in a batch bioreactor using two strains of xylose-fermenting yeast

Ethanol production from biomass-derived pentose sugar challenges the development of low cost technologies to produce 2G ethanol. Although some studies describe ethanol production from yeast, few reports describe its manufacturing from hemicelluloses sugars in stirred-tank fermenter under controlled conditions. Experimental assays were performed to evaluate the influence of aeration, agitation rate and initial pH on ethanol production using sugarcane bagasse hemicelluloses hydrolysate by Scheffersomyces stipitis NRRL Y-7124 and Scheffersomyces shehatae UFMG HM 52.2. Ethanol production from these two yeasts was favored by initial pH increase and agitation rate decrease. The maximum fermentative yield was attained by S. stipitis and S. shehatae yeasts at 100 RPM, initial pH 6.50 and under oxygen limited conditions (0.1 and 3.2 h−1). Yield, ethanol productivity and process efficiency in S. shehatae and S. stipitis were 0.42 and 0.16 g g−1, 0.25 and 0.1 g L−1 h−1 and 85 and 31%, respectively. It showed that S. shehatae presented the best ethanol production performance. The current study is the first report describing the influence of these variables on hemicelluloses hydrolysates under controlled conditions. It highlights these xylose-fermenting yeasts potential to produce ethanol from biomass.