title: Recycling cellulases by pH-triggered adsorption-desorption during the enzymatic hydrolysis of lignocellulosic biomass.
abstract: Recycling of cellulases is an effective way to reduce the cost of enzymatic hydrolysis for the production of cellulosic ethanol. In this study, we examined the adsorption and desorption behaviors of cellulase at different pH values and temperatures. Furthermore, we developed a promising way to recover both free and bound cellulases by pH-triggered adsorption-desorption. The results show that acidic pH (e.g., pH 4.8) was found to favor adsorption, whereas alkaline pH (e.g., pH 10) and low temperature (4-37 °C) favored desorption. The adsorption of cellulases reached an equilibrium within 60 min at pH 4.8 and 25 °C, leading to approximately 50 % of the added cellulases bound to the substrate. By controlling the pH of eluent (citrate buffer, 25 °C), we were able to increase the desorption efficiency of bound cellulases from 15 % at pH 4.8 to 85 % at pH 10. To recover cellulases after enzymatic hydrolysis, we employed adsorption by fresh substrate and desorption at pH 10 to recover the free cellulases in supernatant and the bound cellulases in residue, respectively. The recycling performance (based on the glucose yield) of this simple strategy could reach near 80 %. Our results provided a simple, low-cost, and effective approach for cellulase recycling during the enzymatic hydrolysis of lignocellulosic biomass.
authors.affiliation: Collaborative Innovation Center of Chemical Science and Engineering, State Key Laboratory of Chemical Engineering, Tianjin Key Laboratory of Membrane Science and Desalination Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Shang
authors.forename: Rongxin
authors.initials: R
authors.lastname: Su
authors.forename: Renliang
authors.initials: R
authors.lastname: Huang
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Qi
authors.forename: Qiujin
authors.initials: Q
authors.lastname: Li
authors.forename: Zhimin
authors.initials: Z
authors.lastname: He
mesh_terms: D000327:Adsorption; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D044602:Cellulases / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism*; D059027:Recycling / Q000379:methods; D013696:Temperature
chemical_list: C036909:lignocellulose; D008031:Lignin; D044602:Cellulases