Preparation of immobilized Trametes pubescens laccase on a cryogel-type polymeric carrier and application of the biocatalyst to apple juice phenolic compounds oxidation

An Overview of Microorganisms Immobilized in a Gel Structure for the Production of Precursors, Antibiotics, and Valuable Products

Using free microorganisms for industrial processes has some limitations, such as the extensive consumption of substrates for growth, significant sensitivity to the microenvironment, and the necessity of separation from the product and, therefore, the cyclic process. It is widely acknowledged that confining or immobilizing cells in a matrix or support structure enhances enzyme stability, facilitates recycling, enhances rheological resilience, lowers bioprocess costs, and serves as a fundamental prerequisite for large-scale applications. This report summarizes the various cell immobilization methods, including several synthetic (polyvinylalcohol, polyethylenimine, polyacrylates, and Eudragit) and natural (gelatin, chitosan, alginate, cellulose, agar-agar, carboxymethylcellulose, and other polysaccharides) polymeric materials in the form of thin films, hydrogels, and cryogels. Advancements in the production of well-known antibiotics like penicillin and cephalosporin by various strains were discussed. Additionally, we highlighted cutting-edge research related to strain producers of peptide-based antibiotics (polymyxin B, Subtilin, Tyrothricin, varigomycin, gramicidin S, friulimicin, and bacteriocin), glusoseamines, and polyene derivatives. Crosslinking agents, especially covalent linkers, significantly affect the activity and stability of biocatalysts (penicillin G acylase, penicillinase, deacetoxycephalosporinase, L-asparaginase, β-glucosidase, Xylanase, and urease). The molecular weight of polymers is an important parameter influencing oxygen and nutrient diffusion, the kinetics of hydrogel formation, rigidity, rheology, elastic moduli, and other mechanical properties crucial for long-term utilization. A comparison of stability and enzymatic activity between immobilized enzymes and their free native counterparts was explored. The discussion was not limited to recent advancements in the biopharmaceutical field, such as microorganism or enzyme immobilization, but also extended to methods used in sensor and biosensor applications. In this study, we present data on the advantages of cell and enzyme immobilization over microorganism (bacteria and fungi) suspension states to produce various bioproducts and metabolites-such as antibiotics, enzymes, and precursors-and determine the efficiency of immobilization processes and the optimal conditions and process parameters to maximize the yield of the target products.

Stabilization of Picea abies Spruce Bark Extracts within Ice-Templated Porous Dextran Hydrogels

Porous hydrogels have brought more advantages than conventional hydrogels when used as chromatographic materials, controlled release vehicles for drugs and proteins, matrices for immobilization or separation of molecules and cells, or as scaffolds in tissue engineering. Polysaccharide-based porous hydrogels, in particular, can address challenges related to bioavailability, solubility, stability, and targeted delivery of natural antioxidant compounds. Their porous structure enables the facile encapsulation and controlled release of these compounds, enhancing their therapeutic effectiveness. In this context, in the present study, the cryogelation technique has been adopted to prepare novel dextran (Dx)-based porous hydrogels embedding polyphenol-rich natural extract from Picea abies spruce bark (SBE). The entrapment of the SBE within the Dx network was proved by FTIR, SEM, and energy-dispersive X-ray spectroscopy (EDX). SEM analysis showed that entrapment of SBE resulted in denser cryogels with smaller and more uniform pores. Swelling kinetics confirmed that higher concentrations of Dx, EGDGE, and SBE reduced water uptake. The release studies demonstrated the effective stabilization of SBE in the Dx-based cryogels, with minimal release irrespective of the approach selected for SBE incorporation, i.e., during synthesis (~3-4%) or post-synthesis (~15-16%). In addition, the encapsulation of SBE within the Dx network endowed the hydrogels with remarkable antioxidant and antimicrobial properties. These porous biomaterials could have broad applications in areas such as biomedical engineering, food preservation, and environmental protection, where stability, efficacy, and safety are paramount.

The Encounter of Biomolecules in Metal-Organic Framework Micro/Nano Reactors

In nature, biochemical reactions often take place in confined spaces, as typically exemplified by cells. As numerous cellular reactors can be integrated to maintain the living system, researchers have made constant efforts to construct cell-like structures for achieving similar transformations in vitro. Micro/nano reactors engineered by polymers and colloids are becoming popular and being applied in many fields, especially there has been an increasing trend toward constructing metal-organic framework (MOF) micro/nano reactors with the thriving of MOF nanotechnologies. Because of the uniform pores of MOFs, the transmission of substances can be regulated more accurately. Along with properties of large specific surface area, functional diversity and precise control of the particle size, MOFs are also ideal platforms for building distinct microenvironments for biological substances. Compared with traditional polymersomes and colloidosomes, the unique characteristics of MOFs render them potent micro/nano reactor shell materials, mimicking cells for applications in enzymatic catalysis, sensing, nanotherapy, vaccine, biodegradation, etc. This review highlights recent signs of progress on the design of MOF micro/nano reactors and their applications in biology, discusses the existing problems, and prospects their promising properties for smarter multifunctional applications.

Magnetically Responsive PA6 Microparticles with Immobilized Laccase Show High Catalytic Efficiency in the Enzymatic Treatment of Catechol

Herewith we report the first attempt towards non-covalent immobilization of Trametes versicolor laccase on neat and magnetically responsive highly porous polyamide 6 (PA6) microparticles and their application for catechol oxidation. Four polyamide supports, namely neat PA6 and such carrying Fe, phosphate-coated Fe and Fe3O4 cores were synthesized in suspension by activated anionic ring-opening polymerization (AAROP) of ε-caprolactam (ECL). Enzyme adsorption efficiency up to 92% was achieved in the immobilization process. All empty supports and PA6 laccase complexes were characterized by spectral and synchrotron WAXS/SAXS analyses. The activity of the immobilized laccase was evaluated using 2,2’-Azino-bis-(3- ethylbenzothiazoline-6-sulfonic acid (ABTS) and compared to the native enzyme. The PA6 laccase conjugates displayed up to 105% relative activity at room temperature, pH 4, 40 °C and 20 mM ionic strength (citrate buffer). The kinetic parameters of the ABTS oxidation were also determined. The reusability of the immobilized laccase-conjugates was proven for five consecutive oxidation cycles of catechol.

Cryostructuring of Polymeric Systems. 55. Retrospective View on the More than 40 Years of Studies Performed in the A.N.Nesmeyanov Institute of Organoelement Compounds with Respect of the Cryostructuring Processes in Polymeric Systems

The processes of cryostructuring in polymeric systems, the techniques of the preparation of diverse cryogels and cryostructurates, the physico-chemical mechanisms of their formation, and the applied potential of these advanced polymer materials are all of high scientific and practical interest in many countries. This review article describes and discusses the results of more than 40 years of studies in this field performed by the researchers from the A.N.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences-one of the key centers, where such investigations are carried out. The review includes brief historical information, the description of the main effects and trends characteristic of the cryostructuring processes, the data on the morphological specifics inherent in the polymeric cryogels and cryostructurates, and examples of their implementation for solving certain applied tasks.

Recent developments in enzyme immobilization technology for high-throughput processing in food industries

The demand for food and beverage markets has increased as a result of population increase and in view of health awareness. The quality of products from food processing industry has to be improved economically by incorporating greener methodologies that enhances the safety and shelf life via the enzymes application while maintaining the essential nutritional qualities. The utilization of enzymes is rendered more favorable in industrial practices via the modification of their characteristics as attested by studies on enzyme immobilization pertaining to different stages of food and beverage processing; these studies have enhanced the catalytic activity, stability of enzymes and lowered the overall cost. However, the harsh conditions of industrial processes continue to increase the propensity of enzyme destabilization thus shortening their industrial lifespan namely enzyme leaching, recoverability, uncontrollable orientation and the lack of a general procedure. Innovative studies have strived to provide new tools and materials for the development of systems offering new possibilities for industrial applications of enzymes. Herein, an effort has been made to present up-to-date developments on enzyme immobilization and current challenges in the food and beverage industries in terms of enhancing the enzyme stability.

Induction, purification, and characterization of a thermo and pH stable laccase from Abortiporus biennis J2 and its application on the clarification of litchi juice

A fungus J2 producing laccase with high yield was screened in soils and identified as Abortiporus biennis. The production of laccase was induced by 0.1 mM Cu²⁺, 0.1 mM tannic acid, and 0.5 M ethanol. The laccase from Abortiporus biennis J2 was purified to electrophoretic homogeneity by a couple of steps. The N-terminal amino acid sequence of the enzyme was AIGPTADLNISNADI. The properties of the purified laccase were investigated. The result showed the laccase from Abortiporus biennis J2 is a thermo and pH stable enzyme. The laccase activity was inhibited by Hg²⁺, Cd²⁺, Fe²⁺, Ag⁺, Cu²⁺, and Zn²⁺, while promoted by Mg²⁺, Mn²⁺ at 10 mM level. Purified laccase was used to the clarification of litchi juice. After treatment with this laccase, the phenolic content of litchi juice had been found to be greatly reduced along with an increase in the clarity of the juice. The result indicated the potential of this laccase for application in juice procession.

Evaluation of p-cresol degradation with polyphenol oxidase (PPO) immobilized in various matrices

p-Cresol is an environmental pollutant due to its vast use, toxicity and persistence, nevertheless, its degradation in an enzyme is unclear. In this study, we used Pleurotus sp. isolate VLECK02 polyphenol oxidase (PPO) for the determination of p-cresol degradation. On the basis of UV, FT-IR and chromatographic (HPLC and GC–MS) analysis, 4-methylcatechol was identified as the main metabolite of p-cresol catabolism. In addition, batch and semi-continuous degradation of p-cresol (10 and 20 mM) were studied and compared by free and immobilized PPO in different matrices like sodium alginate (SA), sodium alginate–polyvinyl alcohol (SA–PVA) and sodium alginate–polyvinyl alcohol–silver nanoparticles (SA–PVA–AgNPs). The experimental data showed that an enzyme (PPO) immobilized in SA–PVA–AgNPs was completely degraded p-cresol at initial concentrations of 10 and 20 mM within 30 h. These results suggest that the enzyme immobilized in SA–PVA–AgNPs has achieved higher degradation rates at a given time than free PPO and PPO immobilized in SA–PVA and SA. The SA–PVA–AgNPs and SA–PVA immobilized enzyme could be reused for more than 12 and 8 cycles, respectively, without losing any degradation capacity. Moreover, the immobilized PPO showed higher tolerance to various temperatures and pH than free PPO. Hence, immobilized PPO could be useful for the bioremediation of environment contaminated with phenolic compounds like p-cresol.

Overproduction of laccase from a newly isolated Ganoderma lucidum using the municipal food waste as main carbon and nitrogen supplement

A strain of Ganoderma lucidum was separated and identified according to its morphological characteristics and phylogenetic data. The fungus is a laccase producer and it can secrete laccase using the municipal food waste (FW) as carbon and nitrogen supplement. After the statistic optimization, a laccase activity of 42,000 ± 600 U/l was obtained at 500 ml flask level and the activity is 12,000 U/l higher than that obtained by fermenting glucose and peptone, indicating that the use of FW to produce laccase not only reduces production cost, but also improves laccase activity. In 15 l bioreactor, FW is also suitable for laccase production and the maximum laccase activity reached 54,000 U/l. Moreover, some details of laccase overproduction using FW were investigated. The G. lucidum consumes FW by secreting a series of hydrolases and proteases and the improvement of laccase activity is because FW induces over-expression of three isoenzymes by polyacrylamide gel electrophoresis analysis.

Biodegradation of 2,4-dinitrophenol with laccase immobilized on nano-porous silica beads

Many organic hazardous pollutants, including 2,4-dinitrophenol (2,4-DNP), which are water soluble, toxic, and not easily biodegradable make concerns for environmental pollution worldwide. In the present study, degradation of nitrophenols-contained effluents by using laccase immobilized on the nano-porous silica beads was evaluated. 2,4-DNP was selected as the main constituent of industrial effluents containing nitrophenols. The performance of the system was characterized as a function of pH, contact time, temperature, pollutant, and mediator concentrations. The laccase-silica beads were employed in a mixed-batch reactor to determine the degradation efficiency after 12 h of enzyme treatment. The obtained data showed that the immobilized laccase degraded more than 90% of 2,4-DNP within 12 h treatment. The immobilization process improved the activity and sustainability of laccase for degradation of the pollutant. Temperatures more than 50°C reduced the enzyme activity to about 60%. However, pH and the mediator concentration could not affect the enzyme activity. The degradation kinetic was in accordance with a Michaelis-Menten equation with Vmax and Km obtained as 0.25-0.38 μmoles/min and 0.13-0.017 mM, respectively. The stability of the immobilized enzyme was maintained for more than 85% of its initial activity after 30 days. Based on the results, it can be concluded that high resistibility and reusability of immobilized laccase on CPC-silica beads make it considerable choice for wastewater treatment.

Preparation of Laccase Immobilized Cryogels and Usage for Decolorization

Poly(methyl methacrylate-co-glycidyl methacrylate) (poly(MMA-co-GMA)) cryogels were synthesized by radical cryopolymerization technique. Then, laccase enzyme was covalently attached to the cryogel and characterized by using swelling studies and SEM and EDX analyses. Kinetic properties and optimum conditions of the immobilized and free laccase were studied and it was found that of the immobilized laccase was lower than that of free laccase. of the immobilized laccase was increased upon immobilization. Optimum pH was found to be 4.0 for each type of laccase, while optimum temperature was shifted to the warmer region after the immobilization. It was also found that thermal stability of the immobilized laccase was higher than that of free laccase. Immobilized laccase could be used for 10 times successive reuse with no significant decrease in its activity. Also, these laccase immobilized cryogels were successfully used for the decolorization of seven different dyes.