Saccharification and Ethanol Production of Corn Wastes Using a Locally Produced <i>Trichoderma atroviride</i> Enzymatic Cocktail

This study investigated the efficiency of a homemade enzymatic cocktail from <i>Trichoderma atroviride</i> (HTM strain) in the saccharification of corn straw (CS) and corn cob (CC), aiming at cellulosic ethanol production. The blend of cellulases and hemicellulases, obtained through solid-state fermentation, exhibited high levels of β-glucosidase (374.91 U/g) and xylanase (920 U/g). The β-glucosidase from this cocktail presented optimal activity and stability at pH and temperature ranges suitable for lignocellulose bioconversions (4.5-5.0 and 50 °C) and was employed in the saccharification of alkali-pretreated CC and CS (PTCC and PTCS, respectively). The fed-batch hydrolysis, performed with 30 CBU/g (<i>cellobiase unit</i>) cellulose and 35% solid (w/v), released the highest concentration of total reducing sugars (TRS) in PTCC (15.86 g/L). When 1% Tween 20 was added to the reaction mixture, a total of 30.37 g/L TRS was detected in PTCC hydrolysate, representing an increase of 91.4% in comparison to the hydrolysis without the surfactant. The alcoholic fermentation of the PTCC hydrolysate resulted in a theoretical conversion yield of 83.48%. These data indicated the feasibility of using <i>T. atroviride</i> as a low-cost enzymatic source and the combined strategy of fed-batch mode and surfactant in improving the hydrolytic and fermentative efficiencies.