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Effects of Gleditsia saponin on high-solids enzymatic hydrolysis of furfural residues
- Xing, Yang, Ji, Li, Liu, Zhi-ping, Zhang, Wei-ming, Jiang, Jian-xin
- Industrial crops and products 2015 v.64 pp. 209-214
- Gleditsia, X-ray photoelectron spectroscopy, additives, adsorption, cellulose, enzymatic hydrolysis, enzyme activity, enzymes, furfural, lignin, micelles, saponins, surfactants
- Surfactants are popular additives for the prevention of the inhibitory effect of lignin on cellulolytic enzymes. Saponin is a type of natural surfactant extracted from Gleditsia spp. In this study, the effect of saponin on the high-solids-loading enzymatic hydrolysis of furfural residues (FRs) with a lignin content of 45% was investigated. The optimal dosage of Gleditsia saponin (GS) was determined to be 25-fold greater than its critical micelle concentration (CMC; 0.16g/L). The addition of GS increased the cellulose conversion by up to 52.63% in high-solids-loading enzymatic hydrolysis. Due to the addition of GS, a maximum cellulose conversion of 74.88% was achieved after FRs had hydrolyzed for 120h at a solids loading of 20% (w/w) with 30 filter paper unit (FPU)/g-cellulose. The decrease in cellulose conversion was found to exhibit a linear correlation with an increase in the solids loadings from 20.0% to 27.5% (w/w). The surface structural variations of hydrolytic residues were characterized by X-ray photoelectron spectroscopy (XPS). The results indicated that the carbonyl groups of lignin facilitated the binding of GS to the surface of lignin, which resulted in a decrease in the adsorption of between the enzyme and lignin. Interestingly, GS could maintain enzymatic activity in the supernatants.