Increase in Second Generation Ethanol Production by Different Nutritional Conditions from Sugarcane Bagasse Hydrolysate using a Saccharomyces cerevisiae Native Strain

Abstract

The lignocellulosic materials are an alternative feedstock for ethanol production, because their low cost and high availability. Sugarcane bagasse is an agroindustrial residue that has been identified as a feasible option due to its high sugar content. A second generation process of ethanol production consists of three steps: pre- treatment, enzymatic hydrolysis and fermentation. Two of the most critical aspects during hydrolysate fermentation to obtain high ethanol productivity are: yeast selection and nutrient supplementation. Native yeast strains isolated from extreme environments as sugarcane distilleries could have an easy adaptation to new medium as lignocellulosic biomass hydrolysate that could contains high inhibitors concentrations. The objective of this study was to evaluate different nutrients supplementation (ZnSO₄, MgSO₄, MnSO₄ and KH₂PO₄) in a sugarcane bagasse hydrolysate to increase ethanol productivity during fermentation with a native strain of Saccharomyces cerevisiae (202-3). One central composite design with a response surface methodology (RSM) was performed in order to identify the optimal experimental condition. The best results were 0.480 g ethanol g glucose^-1 ethanol yield and 1.72 g^-1 L^-1 h^-1 ethanol volumetric productivity on a hydrolysate supplemented with 1.0 g L^-1 KH₂PO₄, 0.05 g L^-1 MgSO₄, 0.01 g L^-1 ZnSO₄ and 0.001 g L^-1 MnSO₄