Magnetic graphene oxide as a platform for the immobilization of cellulases and xylanases: Ultrastructural characterization and assessment of lignocellulosic biomass hydrolysis

[EN] For producing second-generation ethanol (cellulosic ethanol) and other value-added bioproducts, magnetic graphene oxide (GO-MNP) was synthesized in this work and used as the immobilization support for an industrial cellulase-and xylanase-containing preparation. GO-MNP characterization by TEM, SEM and ATR-FTIR spectroscopy showed that the magnetic nanoparticles are homogeneously distributed onto the GO sheets surface. The enzymatic preparation was immobilized by means of carbodiimide cross-linking chemistry using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide (NHS). The supported final biocatalyst (GO-MNP-Enz) showed high activity for the hydrolysis of pretreated sugarcane bagasse (PSB) and presented relative endoglucanase, xylanase, beta-glucosidase, and beta-xylosidase activities of 70%, 66%, 88%, and 70%, respectively, after 10 cycles of hydrolysis of their respective substrates. The biocatalyst also maintained approximately 50% and 80% of its efficiency for cellulose and xylan hydrolysis, respectively, being the TOF (g.g(-1).h(-1)) the highest observed when compared with previous results reported in literature. These findings suggest that GO-MNP-Enz may be a prospective candidate for industrial applications such as second-generation ethanol production. (C) 2020 Elsevier Ltd. All rights reserved.
Sao Paulo State Research Support Foundation (FAPESP) contract number 2018/06241e3 funding this work. Coordination of Improvement of Higher Education Personnel (CAPES) funding the doctoral scholarship of Fernando Roberto Paz-Cedeno in Brazil and in the Universitat Politecnica de Valencia (UPV), Institute of Chemical Technology (ITQ), Valencia, Spain. Authors acknowledge financial support from PGC2018-097277-B-100 (MCIU/AEI/FEDER,UE) project and Severo Ochoa Program (SEV-2016-0683).