Immobilization of Chromobacterium viscosum lipase on Eudragit S-100: coupling, characterization and kinetic application in organic and biphasic media

Dynamic Modelling of Enzymatic Hydrolysis of Oil Using Lipase Immobilized on Zeolite

Immobilization has been proposed as a way to simplify the separation and repeated reuse of enzymes, which is essential for their feasible application at industrial scales. However, in their immobilized form, enzyme activity is fully utilized, due primarily to the additional diffusion limitations. Here, the immobilization of lipase on zeolite and its use in catalyzing oil hydrolysis is studied. Adsorption isotherms were investigated, and the data identified the model that best describes the process, which is the Sips model. The adsorption capacity of zeolite was determined as 62.6 mg/g, which is relatively high due to the high porosity of the support. The rate of enzymatic hydrolysis of olive oil, using the immobilized lipase, was determined at a pH of 7 and a temperature of 40 °C and was compared to that when using free enzymes. The results determined the parameters for a diffusion-reaction model. The effects of both the surface reaction and diffusion were found to be significant, with a slightly higher effect from surface reactions.

Bioinspired Pseudozwitterionic Hydrogels with Bioactive Enzyme Immobilization via pH-Responsive Regulation

Hydrogels are hydrated networks of flexible polymers with versatile biomedical applications, and their resistance to nonspecific protein adsorption is critical. On the other hand, functionalization with other biomacromolecules would greatly enhance their biotechnological potential. The aim of this research is to prepare low fouling hydrogel polymers for selective protein immobilization. Initially, hydrogels were prepared by controlling the composition ratios of 2-carboxyethyl acrylate (CA) and 2-dimethylaminoethyl methacrylate (DMAEMA) monomers in an N, N-methylene-bis-acrylamide (NMBA) cross-linked free radical polymerization reaction. This series of hydrogels (C1D9 to C9D1) were then analyzed by X-ray photoelectron spectroscopy (XPS) and dynamic laser scattering to confirm the actual polymer ratios and surface charge. When the composition ratio was set at CA:6 vs DMEAMA:4 (C6D4), the hydrogel showed nearly neutral surface charge and an equivalent reaction ratio of CA vs DMAEMA in the hydrogel. Subsequent analysis showed excellent antifouling properties, low blood cell adhesion, hemocompatibility, and platelet deactivation. Moreover, this hydrogel exhibited pH responsiveness to protein adsorption and was then used to facilitate the immobilization of lipase as an indication of active protein functionalization while still maintaining a low fouling status. In summary, a mixed-charge nonfouling pseudozwitterionic hydrogel could be prepared, and its pH-responsive adsorption holds potential for designing a biocompatible tissue engineering matrix or membrane enzyme reactors.

Production of alpha-amylase from Aspergillus oryzae for several industrial applications in a single step

A one-step method as a strategy of alpha-amylase concentration and purification was developed in this work. This methodology requires the use of a very low concentration of biodegradable polyelectrolyte (Eudragit(®) E-PO) and represents a low cost, fast, easy to scale up and non-polluting technology. Besides, this methodology allows recycling the polymer after precipitation. The formation of reversible soluble/insoluble complexes between alpha-amylase and the polymer Eudragit(®) E-PO was studied, and their precipitation in selected conditions was applied with bioseparation purposes. Turbidimetric assays allowed to determine the pH range where the complexes are insoluble (4.50-7.00); pH 5.50 yielded the highest turbidity of the system. The presence of NaCl (0.05M) in the medium totally dissociates the protein-polymer complexes. When the adequate concentration of polymer was added under these conditions to a liquid culture of Aspergillus oryzae, purification factors of alpha-amylase up to 7.43 and recoveries of 88% were obtained in a simple step without previous clarification. These results demonstrate that this methodology is suitable for the concentration and production of alpha-amylase from this source and could be applied at the beginning of downstream processing.

A novel reactive perstraction system based on liquid-core microcapsules applied to lipase-catalyzed biotransformations

A novel reactive perstraction system has been developed based on liquid-core capsules, involving an enzyme-catalyzed reaction coupled with simultaneous in situ product recovery. Lipase-catalyzed reactions, hydrolysis of triprionin and nitrophenyl laurate, were selected to test the system and demonstrate the feasibility of immobilization of enzymes to the membranes of liquid-core capsules and the ability to extract hydrophobic products of the reaction within the capsule core. The lipase from Candida rugosa was immobilized to the microcapsules by adsorption and by covalent binding through activation with glutaraldehyde. In both cases improved temperature and operational stability were achieved. Both types of immobilization resulted in a basic shift of the pH optimum for activity, from 7.5 to 9.0. The presence of an organic phase within the capsule core allowed direct product separation and lead to a decrease in product inhibition of the lipase-catalyzed reaction.