Batch fermentation of hexoses and pentoses for production of ethanol using Scheffersomyces stipitis

The use of all sugars constituents in the plant biomass is important in the biorefinery context. The objective of this study was thus to investigate ethanol production by Scheffersomyces stipitis in media simulating the sugars composition of cellulose and hemicelluloses hydrolysates from sugarcane bagasse and mixtures thereof. The assays were performed in a fermentator containing 1,2 l of medium, with 1,0 g l^-1 initial cell concentration, incubated at 30ºC, 150 rpm, 0.4 vvm (k_La = 4 h^-1) and 6.0 pH initial for 60 h. Under the experimental conditions simulated sugarcane bagasse hemicellulosic (xylose 34  g l^-1, glucose 2.5  g l^-1 and arabinose 5.6  g l^-1), cellulosic (glucose, 38  g l^-1) and mixture (xylose 12.7 g l^-1, glucose 21 g l^-1 and arabinose 1.47 g l^-1) hydrolysates, the yeast showed ethanol production 15.6, 16.4 and 12.9 g l^-1; cell growth 6.0, 6.6 and 6.6 g l^-1; ethanol yield 0.47, 0.44 and 0.44 g g^-1; volumetric productivity 0.33, 0.45 and 0.36 g l^-1 h^-1 and efficiency 91%, 86.6% and 84.5%, respectively. No significant difference was found between fermentation parameters of media simulating cellulose and hemicelluloses hydrolysates and mixtures thereof, which enables development of joint utilization of C5 and C6 fractions of plant biomass aimed ethanol production.
Acknowledgments: CAPES, CNPq, FAPESP