Cellulase mimicking nanomaterial-assisted cellulose hydrolysis for enhanced bioethanol fermentation: an emerging sustainable approach

Abstract

The hydroxyl groups adjacent to the β-1,4 glycosidic linkages in cellulose offer a crystalline structure, which makes depolymerization a difficult task. In the present study, a green synthesized nanomaterial, functionalized few-layer graphene (FFG) possessing exclusive cellulase enzyme mimicking properties, was exploited for the depolymerization of corn cob (CC)-derived cellulose moieties. Here, we studied the combined effect of cellulase and a very low concentration of FFG (0.02 wt% of biomass) on CC-derived cellulose hydrolysis, demonstrating 38% increase in hydrolysis compared to the control (i.e. without FFG). Most importantly, hydrolysis experiments were performed under mild conditions, i.e. at 50 °C, generating fermentable sugars without the formation of any inhibitor compounds. Furthermore, hydrolyzed CC cellulose was employed for bioethanol fermentation by Saccharomyces cerevisiae which produced 1.53 times higher ethanol in the presence of FFG. The residual solid part was further utilized for the formation of cellulose based nano-composite films. Here, we tried to develop a zero waste process by utilizing each component which can be an attractive sustainable option. To the best of our knowledge, this is the first report on the cellulase mimicking activity of FFG nanosheets and their application in the hydrolysis of CC cellulose for improved bioethanol production, which can negate the need for costly cellulase enzymes required for biomass hydrolysis. Hence, the FFG-associated biomass to bioethanol process may pave the way toward the development of green sustainable biofuel technology for its foremost use as transport fuel.