Hydrolysis and fermentation of brewer’s spent grain by Neurospora crassa

In this study, the ethanol production by the mesophilic fungus Neurospora crassa from BG was studied and optimized concerning the induction of lignocellulose degrading enzymes and the production phase as well. The production of cellulolytic and hemicellulolytic enzymes was studied under solid-state cultivation (SSC). SSC in a laboratory horizontal bioreactor using the optimized medium, WS and BG in the ratio 1:1 and initial moisture level 61.5%, allowed the large scale production of the multienzymatic system. Similar yields with those from flasks experiments, as high as 1073, 56, 4.2, 1.6, 3.1, 5.7 and 0.52 U g−1 carbon source of xylanase, endoglucanase, cellobiohydrolase, β-glucosidase, α-l-arabinofuranosidase, acetyl esterase and feruloyl esterase, respectively, were obtained. Chromogenic (fluorogenic) 4-methylumbelliferyl substrates were used to characterize the major activities of the multienzyme component, after the separation by isoelectric focusing (IEF) electrophoresis. Alkali pre-treated BG was used for ethanol production. A yield of about 74 g of ethanol kg−1 dry BG (5, 6 g L−1) was obtained under optimum conditions (aeration 0.1 vvm, pre-treatment with 1 g NaOH 10 g−1 dry BG).