Establishing the Feasibility of Using β-Glucosidase Entrapped in Lentikats and in Sol–Gel Supports for Cellobiose Hydrolysis

Abstract

β-Glucosidases represent an important group of enzymes due to their pivotal role in various biotechnological processes. One of the most prominent is biomass degradation for the production of fuel ethanol from cellulosic agricultural residues and wastes, where the use of immobilized biocatalysts may prove advantageous. Within such scope, the present work aimed to evaluate the feasibility of entrapping β-glucosidase in either sol-gel or in Lentikats supports for application in cellobiose hydrolysis, and to perform the characterization of the resulting bioconversion systems. The activity and stability of the immobilized biocatalyst over given ranges of temperature and pH values were assessed, as well as kinetic data, and compared to the free form, and the operational stability was evaluated. Immobilization increased the thermal stability of the enzyme, with a 10 °C shift to an optimal temperature in the case of sol-gel support. Mass transfer hindrances as a result of immobilization were not significant, for sol-gel support. Lentikats-entrapped glucosidase was used in 19 consecutive batch runs for cellobiose hydrolysis, without noticeable decrease in product yield. Moreover, encouraging results were obtained for continuous operation. In the overall, the feasibility of using immobilized biocatalysts for cellobiose hydrolysis was established.

A multicomponent system based on a blend of agroindustrial wastes for the simultaneous production of industrially applicable enzymes by solid-state fermentation

“…Hydrolysis was determined by monitoring the release of p-nitrophenol at 410 nm with reference to a standard curve prepared using p-nitrophenol. Dne unit of β-glucosidase activity was defined as the amount of enzyme required to release of 1 μmol of p-nitrophenol under the assay conditions described (Figueira et al, 2013).…”

Cost-efficient entrapment of β-glucosidase in nanoscale latex and silicone polymeric thin films for use as stable biocatalysts

“…Enzyme deactivation followed first order kinetics. The E a(d) and half-lives of latex-and silicone-immobilized BGL were higher than those reported earlier for sol-gel-and lentikatsimmobilized BGL, showing a more stable nature than latter ones (Figueira et al, 2013). The increased stability up to 60°C with half-life of 245 h and E a(d) of 337 and 356 kJ mol À1 for free and controlled pore silica-immobilized BGL (Calsavara et al, 2001) have been reported earlier.…”

“…The increased stability up to 60°C with half-life of 245 h and E a(d) of 337 and 356 kJ mol À1 for free and controlled pore silica-immobilized BGL (Calsavara et al, 2001) have been reported earlier. Increased optimum temperature and thermal stabilities of BGL immobilized on chitosan (Bissett & Sternberg, 1978), eupergit C (Tu et al, 2006), silk fibroin nano-particles (Zhou & Zhang, 2011), sol-gel (Figueira et al, 2013), gelatin (Nagatomo et al, 2005), iron oxide magnetic nano-particles (Verma et al, 2013) and polyethylene granules (Nosworthy, Kondyurin, Bilek, & McKenzie, 2014) have also been reported. Immobilization affects the conformational flexibility of the enzyme, resulting in an increase in enzyme rigidity and heat resistance, which is commonly reflected by an increase in optimum temperature and stability against inactivation.…”

“…Enzymatic degradation of biomass involves the synergistic action of three main categories of cellulases, which include endo-1,4-b-D-glucanase (EC 3.2.1.4), exo-1,4-b-D-glucanase (EC 3.2.1.91) and b-glucosidase (EC 3.2.1.21). Several bacteria and fungi, including aerobes or anaerobes, mesophiles and thermophiles, are known for the production of these cellulolytic enzymes (Figueira, Sato, & Fernandes, 2013;Valenzuela et al, 2014;Zheng, Wang, Lu, Xu, & Sun, 2013). However, the level of extracellular cellulases from bacteria and fungi, which are capable of solubilizing crystalline cellulose extensively, is generally low.…”

“…To date, the immobilization of BGL had been carried out in/on various carriers, including kaolin (Karagulyan et al, 2008), silica gel (Jung et al, 2012), Eupergit C (Khan, Lindahl, Turner, & Karlsson, 2012), iron oxide (Valenzuela et al, 2014), chitosan (Chang et al, 2013), nanoparticles (Cipolatti et al, 2014;Verma et al, 2013), streptavidin-coated magnetic particles (Alftrén, Ottow, & Hobley, 2013), mesoporous titanium oxide (Wei et al, 2013), sol-gel (Figueira et al, 2011(Figueira et al, , 2013, glass microspheres and nylon (Chen et al, 2012). However, for cost effective immobilization of enzymes, much cheaper matrices and a simple but effective stabilization approach should be utilized.…”