Optimization of on-site cellulase preparation for efficient hydrolysis of atmospheric glycerol organosolv pretreated wheat straw

BACKGROUNDThe cost of using cellulase to effectively release fermentable sugars from lignocellulosic substrates is still a major impediment to development of the enzyme-based biorefinery' industry. This study attempted to optimize a cellulase preparation from on-site fermentation to efficiently hydrolyse atmospheric glycerol organosolv (AGO)-pretreated wheat straw. RESULTSAddition of Cu2+, PEG10000, L-ascorbic acid and trehalose in the fermentation medium significantly improved the cellulase production. Use of all the additives enabled enhancement to 45.5% of filter paper cellulase (FPA), 14.7% of -glucosidase (BG) and 32.4% of carboxymethyl cellulase (CMCase). With the on-site production of crude cellulase, accessory enzymes (-glucosidase (BG), xylanase and lysozyme) and additives (tea saponin (TS) and cationic polyacrylamide (c-PAM)) were found to facilitate the hydrolysis of AGO-pretreated substrates effectively. The optimized cellulase mixture allowed 96% of enzymatic hydrolysis at 5 FPU g(-1) for 48 h on addition of 11.5 U g(-1) BG, 180 U g(-1) xylanase, 45 U g(-1) lysozyme, 10 mg g(-1) TS and 2 mg g(-1) C-PAM, which was twice that of the crude cellulase broth. CONCLUSIONCellulase customization for specific substrate hydrolysis with on-site produced broth produced an efficient pathway to lower the enzyme cost in the ongoing lignocellulosic biorefining industry. (c) 2018 Society of Chemical Industry