Simplification of the biomass to ethanol conversion process by using the whole medium of filamentous fungi cultivated under solid-state fermentation

Bioprocess engineering developments aimed at improving the efficiency of biomass conversion into fuels and chemicals can make an important contribution to an environmentally sustainable society. Here, a novel simplified configuration is proposed for the conversion of biomass to ethanol, using whole-medium enzymatic cocktails (WM) and enzymatic extracts (EE) from different filamentous fungi (Trichoderma reesei, Aspergillus niger, and Aspergillus oryzae), cultivated under solid-state fermentation (SSF), for the hydrolysis of steam-exploded sugarcane bagasse (SESB). The hydrolyzed material derived from the saccharification of SESB using the combinations A. niger WM + T. reesei EE, A. oryzae WM + A. niger EE, and A. niger EE + T. reesei WM resulted in the best biomass conversion yields (66, 65, and 64% of the theoretical reducing sugar yields, respectively). The best ethanol production (84% of the theoretical yield) was obtained using the material hydrolyzed by a combination of A. oryzae WM + A. niger EE. The enzymatic conversion of SESB using on-site produced enzymes from the whole SSF cultivation medium, followed by an ethanol production step, is a potential configuration for the biomass to ethanol conversion process. This novel simplified configuration would enable the use of a single reactor system, avoiding the need for additional separation steps.