Stability of the Cellic CTec2 enzymatic preparation immobilized onto magnetic graphene oxide: Assessment of hydrolysis of pretreated sugarcane bagasse

Abstract

Sugarcane bagasse (SB) was subjected to enzymatic hydrolysis using an enzyme cocktail immobilized on magnetic graphene oxide particles (GO-MNP). The thermal, storage, pH, and operational stabilities of the immobilized enzymes, including exoglucanase, endoglucanase, β-glucosidase, xylanase, and β-xylosidase, were evaluated. The half-life of the biocatalyst (GO-MNP-Enz) was longer than that of the free enzymes at temperatures above 45 °C, with the exception of endoglucanase. SB was subjected to pretreatments generating sulfite-NaOH pretreated SB (SSB) and chlorite pretreated SB (CSB). The enzymatic hydrolysis of SSB and CSB was evaluated using free enzymes and GO-MNP-Enz. The cellulose and xylan conversion of SSB using free enzymes was higher than using GO-MNP-Enz; however, a similar result was obtained after 72 h. This did not occur in the hydrolysis of CSB, in which at the end of 72 h, conversion using GO-MNP-Enz did not reach the levels obtained with free enzymes. GO-MNP-Enz was successfully reused in several SSB hydrolysis cycles, maintaining an efficiency of approximately 80% and presenting the highest turnover frequency when compared with previous results reported in literature. Finally, these results show that the immobilization of cellulases and xylanases improves their operational stability and the obtained GO-MNP-Enz can be used for various SB hydrolysis cycles.