Saccharification and Ethanol Production of Corn Wastes Using a Locally Produced Trichoderma atroviride Enzymatic Cocktail.

This study investigated the efficiency of a homemade enzymatic cocktail from Trichoderma atroviride (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 (cellobiase unit) 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 T. atroviride as a low-cost enzymatic source and the combined strategy of fed-batch mode and surfactant in improving the hydrolytic and fermentative efficiencies.