Enhancing cellulases through synergistic β-glucosidases for intensifying cellulose hydrolysis

Abstract

β-glucosidases (BGs) are key enzymes in cellulose hydrolysis, being the rate-limiting enzyme that is regulated by feedback inhibition from its own product—glucose. Due to which low hydrolysis yields are observed thus affecting overall ethanol yield per ton biomass. In this study, hydrolysis yields influence as a function of BG deficiency, supplementation, and its synergy in cellulase cocktails were investigated. Results show that commercial cellulase preparations were low in BG and produce hydrolysis yields below 60 % in 12 h. On blending commercial preparations with BGs (from fungal and bacterial sources), the degree of synergism was observed greater than 1, indicating that the components depicted synergistic behaviour in the mixture. A triple blend cellulase cocktail comprising commercial preparation, and two different BG preparations were optimized using the mixture design approach based on the synergism demonstrated. According to the findings, the in-house optimized cocktail (C-Mix) was able to hydrolyze six different two-stage treated LBM feedstocks and release more than 900 mg/g of glucose. The stability of the optimized cocktail was also enhanced two-fold due to strong synergistic interactions. Thus, a simple blending of BGs in the commercial preparations can be a sustainable approach for developing effective cocktails and intensifying cellulose hydrolysis.