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

• Published in: Frontiers in energy research 2014-01, Vol.2
• Main Authors: Du, Ruoyu, Su, Rongxin, Zhang, Mingjia, Qi, Wei, He, Zhimin
• Format: Article
• Language: English
• Subjects: Cellulase; Enzyme recycling; High-solids; Lignocellulose; Simultaneous saccharification and fermentation (SSF)
• ISSN: 2296-598X; 2296-598X
• DOI: 10.3389/fenrg.2014.00024

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 two-fold increased ethanol outputs and reduce enzyme costs by over 50%. The ethanol concentration in each cycle can be achieved at levels greater than 40 g/L.