Synergistic β-glucosidases for improving cellulases recyclability and biomass enzymatic saccharification in wheat straw.

Cellulases required for the conversion of biomass to sugars contribute to a significant part of the final bioethanol cost in the overall lignocellulosic biorefinery. It has been proven that recycling cellulases for saccharification is a viable method to lower the cost of the enzymatic hydrolysis process. Any method for recycling enzymes must begin with a stable cellulase cocktail that can withstand operational recycling conditions. The majority of commercial cellulase preparations contain a small quantity of β-glucosidases (BG), which lowers overall recyclability and causes low hydrolysis yields. This study examines the use of synergistic β-glucosidases (Atu BG3II and Pfu BG1 from Aspergillus tubingensis and Pyrococcus furiosus , respectively) to enhance the recyclability of cellulases during the hydrolysis process. It was able to recycle a significant amount of cellulases by recycling the insoluble solid fraction and liquid fraction following enzymatic hydrolysis of two-step treated wheat straw (ts-WS). In addition, the in-house cellulase cocktail (C-Mix) retained β-glucosidase activity and demonstrated glucose productivity of 18.9 g/L/h at 5% loading and enzyme efficiency (0.41 g of glucose per mg of protein) as Atu BG3II and Pfu BG1 did not adsorb significantly to the biomass. This resulted in a 3.5-fold improvement in the recyclability and a 33% increase in the hydrolysis yield during the study. Therefore, all these results signify better cellulase recovery using two-step treated lignocellulose and stable cellulase cocktails, demonstrating great potential for enzymatic recycling. [Display omitted] • Cellulase recyclability is affected by synergistic β-glucosidase supplementation. • Enzyme adsorbed solid residue can be recycled back enabling maximum enzyme recovery. • Atu BG3 and Pfu BG1 supplementation in cellulase AC led higher hydrolysis yield. • Two-step treatment lead to reduced biomass recalcitrance favouring recyclability. [ABSTRACT FROM AUTHOR]