Cellulases immobilization on chitosan-coated magnetic nanoparticles: application for Agave Atrovirens lignocellulosic biomass hydrolysis

Abstract

In the present study, Trichoderma reesei cellulase was covalently immobilized on chitosan-coated magnetic nanoparticles using glutaraldehyde as a coupling agent. The average diameter of magnetic nanoparticles before and after enzyme immobilization was about 8 and 10 nm, respectively. The immobilized enzyme retained about 37 % of its initial activity, and also showed better thermal and storage stability than free enzyme. Immobilized cellulase retained about 80 % of its activity after 15 cycles of carboxymethylcellulose hydrolysis and was easily separated with the application of an external magnetic field. However, in this reaction, K was increased eight times. The immobilized enzyme was able to hydrolyze lignocellulosic material from Agave atrovirens leaves with yield close to the amount detected with free enzyme and it was re-used in vegetal material conversion up to four cycles with 50 % of activity decrease. This provides an opportunity to reduce the enzyme consumption during lignocellulosic material saccharification for bioethanol production.

Immobilization of Cellulase on a Functional Inorganic–Organic Hybrid Support: Stability and Kinetic Study

“…Moreover, as an effect of immobilization, thermal vibrations of cellulase biomolecules were reduced, which limited conformational changes caused by heat and helped to maintain the proper globular structure of the entire biomolecule [36,37]. Similar findings to those presented in this study were reported by Sanchez-Ramirez et al, who used another inorganic-organic hybrid support (chitosan-coated magnetic nanoparticles) for covalent immobilization of Trichoderma reesei cellulase, and found that the resulting biocatalytic system exhibited its maximum activity at 60 • C. In addition, after 3 h of incubation at that temperature, it retained about 60% of its initial activity; however, an increase in the temperature by 10 • C caused the relative activity to drop significantly, to below 40% [38]. By contrast, cellulase immobilized on the titania-lignin support retained over 80% of its activity after 3 h of incubation at 70 • C.…”

Enhancing Enzymatic Digestibility of Coconut Husk using Nitrogen-assisted Subcritical Water for Sugar Production

“…Hongdan et al [42] reported that by the longer pretreatment time from 0 to 40 min, the (see Figure 7). The maximum sugar yield was obtained at early 8 h of hydrolysis time and then decreased/ tended to be constant exceed 8 h. The phenomenon was confirmed by Sanchez-Ramirez [46]. They showed that the enzyme activity decreased continually at 60 °C incubation after 6 h of enzymatic hydrolysis.…”

Enhanced Performance of Immobilized Xylanase/Filter Paper-ase on a Magnetic Chitosan Support

“…These values represent a 3.3-fold decrease in Ea for immobilized xylanase and a 1.9-fold decrease for immobilized FPase relative to the free enzymes. The changes observed at acidic pH values ( Figure 1) may be explained by the ionic interactions between the enzyme and the support's surface [26]. In addition, internal pH gradients may be formed in enzymes immobilized on porous supports due to diffusion limitations of both substrate and product, resulting in pH changes away from the optimal found in the bulk [9].…”

“…The temperature dependence of the catalytic reaction rate observed through the Arrhenius equation evidences the improvement that immobilization can produce in enzymes' conformational changes as reported by [12,27,28], thus, the immobilized enzymes were able to catalyze the hydrolysis of substrates with a lower Ea when compared to free enzymes. The changes observed at acidic pH values (Figure 1) may be explained by the ionic interactions between the enzyme and the support's surface [26]. In addition, internal pH gradients may be formed in enzymes immobilized on porous supports due to diffusion limitations of both substrate and product, resulting in pH changes away from the optimal found in the bulk [9].…”