Immobilization of β-Glucosidase on Different Supports and Evaluation of Its Activity in Cellobiose Hydrolysis

β-glucosidase was used as catalyst for the hydrolysis of cellobiose, immobilized on different supports, including two silicas (MSNS and MCM-41) and three carbon supports (GAC, BDH and Norit). It was observed that mesoporous nanoparticles are better candidates as supports for the β-glucosidase, and that silica has a better performance, probably due to the presence of silanol groups. The MSNS showed better recovered activity compared to other supports, showing an optimum temperature at 70 0 C and an optimum pH of 5. The enzyme immobilized in MSNS showed results 80% to 98% better than those immobilized on other supports. However, for the recycling test, from the second cycle onwards, the MSNS showed a performance drop of around 40%, reaching a relative activity of 41.9% for both the fourth and the final cycle. MCM-41, on the other hand, did not show as much discrepancy in the recycling test. However, its relative activity in the first cycle was 20% of the activity achieved by MSNS, at its optimum temperature of 60 0 C. Such results indicate that the smaller particle size favours enzymatic activity. Notwithstanding, a larger available intra-pore surface area protects the enzyme from denaturation.

Obtaining lignocellulosic biomass-based catalysts and their catalytic activity in cellobiose hydrolysis and acetic acid esterification reactions

In this work different biochars that were obtained as a by-product from birch chip fast pyrolysis and carbonization were used as is or chemically/physically treated. The characterisation was done using CB hydrolysis and acetic acid esterification.

The effect of pore morphology on the catalytic performance of β-glucosidase immobilized into mesoporous silica

β-Glucosidase (BG) was immobilized by adsorption on wrinkled silica nanoparticles (WSNs) and on tannic acid-templated mesoporous silica nanoparticles (TA-MSNPs). The effect induced by a different morphology of the pores of the sorbent on the catalytic performance of β-glucosidase was investigated. A complete textural and morphological characterization of the two samples was performed by Brunauer–Emmett–Teller (BET) method, Fourier Transform Infrared (FT-IR) and transmission electron microscopy (TEM). The results demonstrated that the catalytic performance of the immobilized enzyme depends on the pores size of sorbent but a key factor is the pores morphology. In fact, the BG immobilized on WSNs and TA-MSNPs (BG/WSNs and BG/TA-MSNPs) shows in both cases good catalytic performances in cellobiose hydrolysis, but the catalyst with the best performance is BG/WSNs, in which the support exhibits a central-radial pore structure and a hierarchical trimodal micro-mesoporous pore size. This peculiar morphology allows the enzyme to settle in a place where the interactions with the walls are maximized, increasing its conformational rigidity. Furthermore, the enzyme is prevalently collocated in the interior of pore so that the pores are not completely capped.