Cellulase Recycling after High-Solids Simultaneous Saccharification and Fermentation of Combined Pretreated Corncob

Abstract

Despite the advantageous prospect of second-generation bioethanol, its final commercialization must overcome the primary cost impediment due to enzyme assumption. To solve this problem, this work achieves high-concentration ethanol fermentation and multi-round cellulase recycling through process integration. The optimal time and temperature of the re-adsorption process were determined by monitoring the adsorption kinetics of cellulases. Both glucose and cellobiose inhibited cellulase adsorption. After 96 h of ethanol fermentation, 40% of the initial cellulase remained in the broth, from which 62.5% of the cellulase can be recycled and reused in fresh substrate re-adsorption for 90 min. Under optimum conditions, i.e., pH 5.0, dry matter loading of 15 wt%, cellulase loading of 45 FPU/g glucan, two cycles of fermentation and re-adsorption can yield twofold increased ethanol outputs and reduce enzyme costs by over 50%. The ethanol concentration in each cycle can be achieved at levels >40 g/L.

Interaction of enzymes with lignocellulosic materials: causes, mechanism and influencing factors

“…Most of researchers investigated adsorption of metal ions, dyes and enzymes on various lignocellulosic substrates at varying temperatures. Their findings were that by increasing temperature, equilibrium constant value was increased, but the time to reach equilibrium remains the same (Medve et al 1994;Sethi et al 1998;Kim et al 2000;Daoud et al 2010;Zheng et al 2013a;2014;Du et al 2014;Sukumaran et al 2017;Houston et al 2019). Some of the researchers have shown adsorption plot at one temperature and used the same equilibrium time for all other temperatures of studies (Sethi et al 1998;Houston et al 2019).…”

Production and Application of Lignin-Based Chemicals and Materials in the Cellulosic Ethanol Production: An Overview on Lignin Closed-Loop Biorefinery Approaches

“…3 and involves the contact of the post-enzymatic hydrolysis liquid phase with fresh lignocellulosic biomass, while the sugars are directed to ethanol fermentation. Examples of this enzyme recycling strategy were carried out in the studies of Steele et al [202], Tu et al [203], Du et al [204], Waenukul et al [205], and Kim et al [206]. The recycling of enzymes from the postenzymatic hydrolysis residue is also possible since it is a lignin-rich material.…”