Simultaneous Saccharification and Fermentation of Pretreated Corn Cobs by Mucor indicus for Ethanol Production

This study evaluates the enzymatic hydrolysis of pretreated corn cobs (PCCs) using a blend of commercial enzymes (Cellulase enzyme blend and Viscozyme L), followed by simultaneous saccharification and fermentation (SSF) with Mucor indicus DSM 2185 for ethanol production. A combination of 2% (vol vol−1) Cellulase enzyme blend and 5.18% (vol vol−1) Viscozyme L, corresponding to an enzyme loading of 48.9 FPU/gPCCs, enabled near-complete hydrolysis of 40 g L−1 PCCs within 6–48 h, achieving 92.66% total carbohydrate conversion into fermentable sugars. In SSF experiments conducted in Erlenmeyer flasks, optimal ethanol production in matrix nutrient medium (MNM) reached 14.95 g L−1, with a conversion coefficient of 0.373 g g−1 at 30 °C over a 48 h period. Scale-up of the bioprocess in a 1.5 L stirred-tank bioreactor at 30 °C resulted in an ethanol concentration of 16.46 g L−1, a total carbohydrate conversion of 86.27%, and a substrate-to-ethanol conversion coefficient of 0.44 g g−1 within 22 h. Minor secondary metabolites, including 0.88 g L−1 xylitol and 0.26 g L−1 glycerol, were also detected. Overall, the results demonstrate the potential of M. indicus in combination with commercial enzyme blends as a scalable strategy for industrial ethanol production.