Bioethanol production from rice straw through an enzymatic route mediated by enzymes developed in-house from Aspergillus fumigatus

This study concerns the in-house development of enzymes from Aspergillus fumigatus and their application in separate hydrolysis and fermentation (SHF) processes for bioethanol production from pre-treated rice straw. The cellulase and hemicellulase activities of A. fumigatus cultivated in NaOH-pretreated rice straw were much higher than those of A. fumigatus cultivated in raw rice straw. A. fumigatus cultivated in raw rice straw exhibited no lignin-degrading manganese peroxidase (MnP) or laccase enzymatic activity. However, A. fumigatus cultivated in NaOH-pretreated rice straw exhibited high lignin-degrading MnP and laccase enzymatic activity. A. fumigatus completely degraded 1.0% NaOH-pretreated rice straw, yielding 27.89 g/L reducing sugar upon loading of 50 g/L. rice straw (based on the original amount of rice straw that went to pretreatment). Saccharification of 1.0% NaOH-pretreated rice straw using 200 FPU/mL crude enzyme released 22.15 g/L. reducing sugars in 20 h. The SHF processes resulted in an ethanol concentration and yield of 9.45 g/L and 83.5%, respectively, with Saccharomyces tanninophilus. (C) 2019 Elsevier Ltd. All rights reserved.