Bioconversion of Lignocellulosic Biomass to Fermentable Sugars by Immobilized Magnetic Cellulolytic Enzyme Cocktails

Abstract

Enzyme cocktails of reusable, highly stable cellulolytic enzymes play an inevitable role in bioconversion of biomass to biofuels economically. Cellulase, xylanase and β-1,3-glucanase bound silica-amine functionalized iron oxide magnetic nanoparticles (ISN-CLEAs) were prepared and used as the biocatalyst for the depolymerization of cellulosic biomass into monomeric sugar in the present study. The FeO-NPs and FeO@SiO-NH-NPs and ISN-CLEAs had an average hydrodynamic size of 82.2, 86.4, and 976.9 nm, respectively, which was confirmed by dynamic light scattering (DLS). About 97% of protein binding was achieved with 135 mM glutaraldehyde at 10 h of cross-linking time and successful binding was confirmed by Fourier transform infrared spectroscopy (FTIR). The ISN-CLEAs exhibited the highest thermal stability of 95% at 50 °C for 2 h and retained extended storage stability of 97% compared to 60% of its free counterpart. Besides, cross-linking allowed ISN-CLEAs reuse for at least eight consecutive cycles retaining over 70% of its initial activity. ISN-CLEAs exhibited approximately 15% increase in carbohydrate digestibility on sugar cane bagasse and eucalyptus pulp than the free enzyme.

Entrapping Digestive Enzymes with Engineered Mesoporous Silica Particles Reduces Metabolic Risk Factors in Humans

“…Batch SM0076 was further treated by heating a suspension of material (220 mg mL −1 ) in an aqueous solution of P123 (31 mg mL −1 ) at 185 °C in an autoclave for 72 h. Batch SM0056 was labeled with magnetic nanoparticles (SM0056‐mag) by adding a suspension of SM0056 in water (120 mg mL −1 ), prepared by sonication for 15 min at a 40% amplitude using an ultrasonicator equipped with a 13 mm probe (Sonics Vibra‐Cell), to an equal volume of a solution of iron oxide magnetic nanoparticles (8 mg mL −1 ) prepared separately according to a modified method previously reported. [ 51 ] After 5 min stirring, the pH was adjusted to 7.0–7.2 using concentrated NH 4 OH and acetic acid aqueous solutions and the silica/magnetic particles suspension was left at room temperature overnight under stirring. MSP particles were recovered by centrifugation, washed, and dried.…”

Enhanced Saccharification and Fermentation of Rice Straw by Reducing the Concentration of Phenolic Compounds Using an Immobilized Enzyme Cocktail

“…The immobilized enzyme cocktail resulted in a better reduction in total phenol concentration as well as enhanced saccharification. The better performance of the immobilized enzyme cocktail over the free enzymes might be primarily associated with higher stability and their synchronized influence after immobilization as described previously . Remarkably, the immobilized enzyme cocktail retained a 73.4% SY after the eighth cycle of reuse.…”

Challenges and Future Perspectives of Promising Biotechnologies for Lignocellulosic Biorefinery

“…The recycle and reuse of crude enzymes is a bottleneck, which results in the waste of fermentation time and enzyme resources. To overcome this limitation, a magnetic nanoparticle has been developed [79]. The surface of iron oxide magnetic nanoparticles was bifunctionalized with silica and amine groups, which can immobilize cellulase, xylanase and β-1,3-glucanase onto the iron oxide magnetic nanoparticles, realizing the recycled usage of enzymes.…”