Stabilization of Immobilized Lipases by Intense Intramolecular Cross-Linking of Their Surfaces by Using Aldehyde-Dextran Polymers

Production of γ-aminobutyric acid by immobilization of two Yarrowia lipolytica glutamate decarboxylases on electrospun nanofibrous membrane

This study harnesses glutamate decarboxylase (GAD) from Yarrowia lipolytica to improve the biosynthesis of γ-aminobutyric acid (GABA), focusing on boosting the enzyme's catalytic efficiency and stability by immobilizing it on nanofibrous membranes. Through recombinant DNA techniques, two GAD genes, YlGAD1 and YlGAD2, were cloned from Yarrowia lipolytica and then expressed in Escherichia coli. Compared to their soluble forms, the immobilized enzymes exhibited significant improvements in thermal and pH stability and increased resistance to chemical denaturants. The immobilization notably enhanced substrate affinity, as evidenced by reduced Km values and increased kcat values, indicating heightened catalytic efficiency. Additionally, the immobilized YlGAD1 and YlGAD2 enzymes showed substantial reusability, maintaining 50% and 40% of their activity, respectively, after six consecutive cycles. These results underscore the feasibility of employing immobilized YlGAD enzymes for cost-effective and environmentally sustainable GABA production. This investigation not only affirms the utility of YlGADs in GABA synthesis but also underscores the advantages of enzyme immobilization in industrial settings, paving the way for scalable biotechnological processes.

Support Enzyme Loading Influences the Effect of Aldehyde Dextran Modification on the Specificity of Immobilized Ficin for Large Proteins

It has been reported that the modification of immobilized glyoxyl-ficin with aldehyde dextran can promote steric hindrances that greatly reduce the activity of the immobilized protease against hemoglobin, while the protease still maintained a reasonable level of activity against casein. In this paper, we studied if this effect may be different depending on the amount of ficin loaded on the support. For this purpose, both the moderately loaded and the overloaded glyoxyl-ficin biocatalysts were prepared and modified with aldehyde dextran. While the moderately loaded biocatalyst had a significantly reduced activity, mainly against hemoglobin, the activity of the overloaded biocatalyst was almost maintained. This suggests that aldehyde dextran was able to modify areas of the moderately loaded enzyme that were not available when the enzyme was overloaded. This modification promoted a significant increase in biocatalyst stability for both biocatalysts, but the stability was higher for the overloaded biocatalyst (perhaps due to a combination of inter- and intramolecular crosslinking).

Integrated Process for Schizochytrium Oil Extraction, Enzymatic Modification of Lipids and Concentration of DHA Fatty Acid Esters Using Alternative Methodologies

Marine microalgae Schizochytrium sp. have a high content of docosahexaenoic acid (DHA), an omega-3 fatty acid that is attracting interest since it prevents certain neurodegenerative diseases. The obtention of a bioactive and purified DHA fatty acid ester using a whole-integrated process in which renewable sources and alternative methodologies are employed is the aim of this study. For this reason, lyophilized Schizochytrium biomass was used as an alternative to fish oil, and advanced extraction techniques as well as enzymatic modification were studied. Microalgal oil extraction was optimized via a surface-response method using pressurized liquid extraction (PLE) obtaining high oil yields (29.06 ± 0.12%) with a high concentration of DHA (51.15 ± 0.72%). Then, the enzymatic modification of Schizochytrium oil was developed by ethanolysis using immobilized Candida antarctica B lipase (Novozym® 435) at two reaction temperatures and different enzymatic loads. The best condition (40 °C and 200 mg of lipase) produced the highest yield of fatty acid ethyl ester (FAEE) (100%) after 8 h of a reaction attaining a cost-effective and alternative process. Finally, an enriched and purified fraction containing DHA-FAEE was obtained using open-column chromatography with a remarkably high concentration of 93.2 ± 1.3% DHA. The purified and bioactive molecules obtained in this study can be used as nutraceutical and active pharmaceutical intermediates of marine origin.

Cross-Linked Enzyme Aggregate (CLEA) Preparation from Waste Activated Sludge

Enzymes are used extensively as industrial bio-catalysts in various manufacturing and processing sectors. However, commercial enzymes are expensive in part due to the high cost of the nutrient medium for the biomass culture. Activated sludge (AS) is a waste product of biological wastewater treatment and consists of microbial biomass that degrades organic matter by producing substantial quantities of hydrolytic enzymes. Recovering enzymes from AS therefore offers a potential alternative to conventional production techniques. A carrier-free, cross-linked enzyme aggregate (CLEA) was produced from crude AS enzyme extract for the first time. A major advantage of the CLEA is the combined immobilization, purification, and stabilization of the crude enzymes into a single step, thereby avoiding large amounts of inert carriers in the final enzyme product. The AS CLEA contained a variety of hydrolytic enzymes and demonstrated high potential for the bio-conversion of complex organic substrates.

Microbial Lipases and Their Potential in the Production of Pharmaceutical Building Blocks

Processes involving lipases in obtaining active pharmaceutical ingredients (APIs) are crucial to increase the sustainability of the industry. Despite their lower production cost, microbial lipases are striking for their versatile catalyzing reactions beyond their physiological role. In the context of taking advantage of microbial lipases in reactions for the synthesis of API building blocks, this review focuses on: (i) the structural origins of the catalytic properties of microbial lipases, including the results of techniques such as single particle monitoring (SPT) and the description of its selectivity beyond the Kazlauskas rule as the “Mirror-Image Packing” or the “Key Region(s) rule influencing enantioselectivity” (KRIE); (ii) immobilization methods given the conferred operative advantages in industrial applications and their modulating capacity of lipase properties; and (iii) a comprehensive description of microbial lipases use as a conventional or promiscuous catalyst in key reactions in the organic synthesis (Knoevenagel condensation, Morita–Baylis–Hillman (MBH) reactions, Markovnikov additions, Baeyer–Villiger oxidation, racemization, among others). Finally, this review will also focus on a research perspective necessary to increase microbial lipases application development towards a greener industry.

A multi-component reaction for covalent immobilization of lipases on amine-functionalized magnetic nanoparticles: production of biodiesel from waste cooking oil

A new approach was used for the immobilization of Thermomyces lanuginosus lipase (TLL), Candida antarctica lipase B (CALB), and Rhizomucor miehei lipase (RML) on amine-functionalized magnetic nanoparticles (Fe3O4@SiO2-NH2) via a multi-component reaction route (using cyclohexyl isocyanide). The used method offered a single-step and very fast process for covalent attachment of the lipases under extremely mild reaction conditions (25 °C, water, and pH 7.0). Rapid and simple immobilization of 20 mg of RML, TLL, and CALB on 1 g of the support produced 100%, 98.5%, and 99.2% immobilization yields, respectively, after 2 h of incubation. The immobilized derivatives were then used for biodiesel production from waste cooking oil. Response surface methodology (RSM) in combination with central composite rotatable design (CCRD) was employed to evaluate and optimize the biodiesel production. The effect of some parameters such as catalyst amount, reaction temperature, methanol concentration, water content for TLL or water-adsorbent for RML and CALB, and ratio of t-butanol (wt%) were investigated on the fatty acid methyl esters (FAME) yield.

Omega-3 production by fish oil hydrolysis using a lipase from Burkholderia gladioli BRM58833 immobilized and stabilized by post-immobilization techniques

Immobilization of lipase from Burkholderia gladioli BRM58833 on octyl sepharose (OCT) resulted in catalysts with higher activity and stability. Following, strategies were studied to further stabilize and secure the enzyme to the support using functionalized polymers, like polyethylenimine (PEI) and aldehyde-dextran (DEXa), to cover the catalyst with layers at different combinations. Alternatively, the construction of a bifunctional layer was studied using methoxypolyethylene glycol amine (NH 2 -PEG) and glycine. The catalyst OCT-PEI-DEXa was the most thermostable, with a 263.8-fold increase in stability when compared to the control condition. When evaluated under alkaline conditions, OCT-DEXa-PEG 10 /Gly was the most stable, reaching stability 70.1 times greater than the control condition. Proportionally, the stabilization obtained for B. gladioli BRM58833 lipase was superior to that obtained for the commercial B. cepacia lipase. Preliminary results in the hydrolysis of fish oil demonstrated the potential of the coating technique with bifunctional polymers, resulting in a stable catalyst with greater catalytic capacity for the production of omega-3 PUFAs. According to the results obtained, it is possible to modulate B. gladioli BRM58833 lipase properties like stability and catalytic activity for enrichment of omega-3 fatty acids.

Chemically modified magnetic immobilized phospholipase A1 and its application for soybean oil degumming

In this paper, the free Phospholipase A₁ (PLA₁) was immobilized on a magnetic carrier. The average particle diameter of the magnetic carrier was 97 ± 1.3 nm, and the average particle diameter of the magnetically immobilized PLA₁ was 105 nm ± 1.3 nm. The enzyme activity was 1940.5 U/g. The magnetic enzyme was chemically modified with formaldehyde, dextran-aldehyde, and dextran-aldehyde-glycine. The proportions of primary amino groups in the modified magnetic immobilized enzyme PLA₁ were 0, 53.5% and 47.3%, respectively. The optimum pH of the enzyme after chemical modification was 6.5. When the system temperature was 60 °C, the magnetically immobilized PLA₁ modified with dextran-aldehyde-glycine had the optimal activity and stability. This chemically modified magnetic immobilized PLA₁ was applied to soybean oil degumming at 60 °C, 6.5 h (reaction time), and 0.10 mg/kg (enzyme dosage). The phosphorus content in the degummed oil was 9.2 mg/kg. The relative enzyme activity was 77.6% after 7 reuses which would be potentially advantageous for industrial applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at (10.1007/s13197-021-05017-4).

Current Status and Future Perspectives of Supports and Protocols for Enzyme Immobilization

The market for industrial enzymes has witnessed constant growth, which is currently around 7% a year, projected to reach $10.5 billion in 2024. Lipases are hydrolase enzymes naturally responsible for triglyceride hydrolysis. They are the most expansively used industrial biocatalysts, with wide application in a broad range of industries. However, these biocatalytic processes are usually limited by the low stability of the enzyme, the half-life time, and the processes required to solve these problems are complex and lack application feasibility at the industrial scale. Emerging technologies create new materials for enzyme carriers and sophisticate the well-known immobilization principles to produce more robust, eco-friendlier, and cheaper biocatalysts. Therefore, this review discusses the trending studies and industrial applications of the materials and protocols for lipase immobilization, analyzing their advantages and disadvantages. Finally, it summarizes the current challenges and potential alternatives for lipases at the industrial level.

Precision targeting of bacterial pathogen via bi-functional nanozyme activated by biofilm microenvironment

Human dental caries is an intractable biofilm-associated disease caused by microbial interactions and dietary sugars on the host's teeth. Commensal bacteria help control opportunistic pathogens via bioactive products such as hydrogen peroxide (H₂O₂). However, high-sugar consumption disrupts homeostasis and promotes pathogen accumulation in acidic biofilms that cause tooth-decay. Here, we exploit the pathological (sugar-rich/acidic) conditions using a nanohybrid system to increase intrinsic H₂O₂ production and trigger pH-dependent reactive oxygen species (ROS) generation for efficient biofilm virulence targeting. The nanohybrid contains glucose-oxidase that catalyzes glucose present in biofilms to increase intrinsic H₂O₂, which is converted by iron oxide nanoparticles with peroxidase-like activity into ROS in acidic pH. Notably, it selectively kills Streptococcus mutans (pathogen) without affecting Streptococcus oralis (commensal) via preferential pathogen-binding and in situ ROS generation. Furthermore, nanohybrid treatments potently reduced dental caries in a rodent model. Compared to chlorhexidine (positive-control), which disrupted oral microbiota diversity, the nanohybrid had significant higher efficacy without affecting soft-tissues and the oral-gastrointestinal microbiomes, while modulating dental health-associated microbial activity in vivo. The data reveal therapeutic precision of a bi-functional hybrid nanozyme against a biofilm-related disease in a controlled-manner activated by pathological conditions.

A comprehensive review on incredible renewable carriers as promising platforms for enzyme immobilization & thereof strategies

Enzymes are the highly versatile bio-catalysts having the potential for being employed in biotechnological and industrial sectors to catalyze biosynthetic reactions over a commercial point of view. Immobilization of enzymes has improved catalytic properties, retention activities, thermal and storage stabilities as well as reusabilities of enzymes in synthetic environments that have enthralled significant attention over the past few years. Dreadful efforts have been emphasized on the renewable and synthetic supports/composite materials to reserve their inherent characteristics such as biocompatibility, non-toxicity, accessibility of numerous reactive sites for profitable immobilization of biological molecules that often serve diverse applications in the pharmaceutical, environmental, and energy sectors. Supports should be endowed with unique physicochemical properties including high specific surface area, hydrophobicity, hydrophilicity, enantioselectivities, multivalent functionalization which professed them as competent carriers for enzyme immobilization. Organic, inorganic, and nano-based platforms are more potent, stable, highly recovered even after used for continuous catalytic processes, broadly renders the enzymes to get efficiently immobilized to develop an inherent bio-catalytic system that displays higher activities as compared to free-counter parts. This review highlights the recent advances or developments on renewable and synthetic matrices that are utilized for the immobilization of enzymes to deliver emerging applications around the globe.

Recent Trends in Biomaterials for Immobilization of Lipases for Application in Non-Conventional Media

The utilization of biomaterials as novel carrier materials for lipase immobilization has been investigated by many research groups over recent years. Biomaterials such as agarose, starch, chitin, chitosan, cellulose, and their derivatives have been extensively studied since they are non-toxic materials, can be obtained from a wide range of sources and are easy to modify, due to the high variety of functional groups on their surfaces. However, although many lipases have been immobilized on biomaterials and have shown potential for application in biocatalysis, special features are required when the biocatalyst is used in non-conventional media, for example, in organic solvents, which are required for most reactions in organic synthesis. In this article, we discuss the use of biomaterials for lipase immobilization, highlighting recent developments in the synthesis and functionalization of biomaterials using different methods. Examples of effective strategies designed to result in improved activity and stability and drawbacks of the different immobilization protocols are discussed. Furthermore, the versatility of different biocatalysts for the production of compounds of interest in organic synthesis is also described.

Stabilization of b-Glucuronidase by Immobilization in Magnetic-Silica Hybrid Supports

β-Glucuronidases are a class of enzymes that catalyze the breakdown of complex carbohydrates. They have well documented biocatalytic applications in synthesis, therapeutics, and analytics that could benefit from enzyme immobilization and stabilization. In this work, we have explored a number of immobilization strategies for Patella vulgata β-Glucuronidase that comprised a tailored combination of biomimetic silica (Si) and magnetic nanoparticles (MNPs). The individual effect of each material on the enzyme upon immobilization was first tested. Three different immobilization strategies for covalent attachment on MNPs and different three catalysts for the deposition of Si particles were tested. We produced nine different immobilized preparations and only two of them presented negligible activity. All the preparations were in the micro-sized range (from 1299 ± 52 nm to 2101 ± 67 nm of hydrodynamic diameter). Their values for polydispersity index varied around 0.3, indicating homogeneous populations of particles with low probability of agglomeration. Storage, thermal, and operational stability were superior for the enzyme immobilized in the composite material. At 80 °C different preparations with Si and MNPs retained 40% of their initial activity after 6 h of incubation whereas the soluble enzyme lost 90% of its initial activity within 11 min. Integration of MNPs provided the advantage of reusing the biocatalyst via magnetic separation up to six times with residual activity. The hybrid material produced herein demonstrated its versatility and robustness as a support for β-Glucuronidases immobilization.

Immobilization of Naringinase from Aspergillus Niger on a Magnetic Polysaccharide Carrier

Naringinase is an enzymatic complex used in the deglycosylation of compounds with a high application potential in the food and pharmaceutical industries. The aim of the study was to immobilize naringinase from Aspergillus niger KMS on a magnetic carrier obtained on the basis of carob gum activated by polyethyleneimine. Response surface methodology was used to optimize naringinase immobilization taking into account the following factors: pH, immobilization time, initial concentration of naringinase and immobilization temperature. The adsorption of the enzyme on a magnetic carrier was a reversible process. The binding force of naringinase was increased by crosslinking the enzyme with the carrier using dextran aldehyde. The crosslinked enzyme had better stability in an acidic environment and at a higher temperature compared to the free form. The immobilization and stabilization of naringinase by dextran aldehyde on the magnetic polysaccharide carrier lowered the activation energy, thus increasing the catalytic capacity of the investigated enzyme and increasing the activation energy of the thermal deactivation process, which confirms higher stability of the immobilized enzyme in comparison with free naringinase. The preparation of crosslinked naringinase retained over 80% of its initial activity after 10 runs of naringin hydrolysis from fresh and model grapefruit juice.

Fine Modulation of the Catalytic Properties of Rhizomucor miehei Lipase Driven by Different Immobilization Strategies for the Selective Hydrolysis of Fish Oil

Functional properties of each enzyme strictly depend on immobilization protocol used for linking enzyme and carrier. Different strategies were applied to prepare the immobilized derivatives of Rhizomucor miehei lipase (RML) and chemically aminated RML (NH₂-RML). Both RML and NH₂-RML forms were covalently immobilized on glyoxyl sepharose (Gx-RML and Gx-NH₂-RML), glyoxyl sepharose dithiothreitol (Gx-DTT-RML and Gx-DTT-NH₂-RML), activated sepharose with cyanogen bromide (CNBr-RML and CNBr-NH₂-RML) and heterofunctional epoxy support partially modified with iminodiacetic acid (epoxy-IDA-RML and epoxy-IDA-NH₂-RML). Immobilization varied from 11% up to 88% yields producing specific activities ranging from 0.5 up to 1.9 UI/mg. Great improvement in thermal stability for Gx-DTT-NH₂-RML and epoxy-IDA-NH₂-RML derivatives was obtained by retaining 49% and 37% of their initial activities at 70 °C, respectively. The regioselectivity of each derivative was also examined in hydrolysis of fish oil at three different conditions. All the derivatives were selective between cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) in favor of EPA. The highest selectivity (32.9 folds) was observed for epoxy-IDA-NH₂-RML derivative in the hydrolysis reaction performed at pH 5 and 4 °C. Recyclability study showed good capability of the immobilized biocatalysts to be used repeatedly, retaining 50-91% of their initial activities after five cycles of the reaction.

Biochemical aspects of lipase immobilization at polysaccharides for biotechnology

The design of immobilized enzyme preparations is an important and relevant area of modern sciences and technologies. Immobilization of enzymes from animal sources (component I) on natural carriers (component II) increases the system stability by protecting the active site of the enzyme from deactivation; facilitates the separation and accelerates the recovery of the enzyme. This makes reuse possible and provides a significant reduction in operating costs. Hydrolytic enzymes (such as lipases) and polysaccharides (such as chitosan) are the most promising of such pairs of components. The main attention here is devoted to the discussion on lipase immobilization on polysaccharide (mainly - chitin and chitosan). Based on the analysis of the available literature, the most adequate method is the immobilization of lipase from porcine pancreas (LPP) on polysaccharide particles (such as chitin or chitosan) pre-treated with ultrasound (to increase the particle surface area) and glutaraldehyde (for particle activation) that shows reasonably high LPP activity and stability. In order to increase further the activity of the lipase, some authors proposed to incorporate a spacer in the form of 1,3-diaminopropane (or 1,3-diaminobutane) prior to activation of the surface of the chitosan particles. In particular cases, the use of chitin (instead of chitosan) may be an alternative solution for biotechnological applications. Recently the idea of constructing "supramolecular enzyme systems" realized in the so-called "coimmobilized multienzymatic systems" strategy. The most fascinating example is the combined assay of a mixture of native LPP, glycerol kinase (from Cellulomonas) and glycerol-3-phosphate oxidase (from Aerococcus viridans) linked by glutaraldehyde to chitosan (as shell for inorganic nanoparticle core). This material was placed on a Pt-electrode as biosensor and was successfully applied for amperometric determination of the triglyceride level in the serum of healthy and diseased person. Thus, the whole innovative research-production sequence is described by Aggarwal V. and Pundir C.S.: from simple components to advanced material and further biomedical application. Thus, the following approach of lipase immobilization appears the most promising for future applications: a few types of lipases or the combination of LPP with some other enzymes immobilized simultaneously on multifunctional carriers (as nanohybrids of inorganic core and polysaccharide shell).

Dextran Aldehyde in Biocatalysis: More Than a Mere Immobilization System

Dextran aldehyde (dexOx), resulting from the periodate oxidative cleavage of 1,2-diol moiety inside dextran, is a polymer that is very useful in many areas, including as a macromolecular carrier for drug delivery and other biomedical applications. In particular, it has been widely used for chemical engineering of enzymes, with the aim of designing better biocatalysts that possess improved catalytic properties, making them more stable and/or active for different catalytic reactions. This polymer possesses a very flexible hydrophilic structure, which becomes inert after chemical reduction; therefore, dexOx comes to be highly versatile in a biocatalyst design. This paper presents an overview of the multiple applications of dexOx in applied biocatalysis, e.g., to modulate the adsorption of biomolecules on carrier surfaces in affinity chromatography and biosensors design, to serve as a spacer arm between a ligand and the support in biomacromolecule immobilization procedures or to generate artificial microenvironments around the enzyme molecules or to stabilize multimeric enzymes by intersubunit crosslinking, among many other applications.

Naturally-derived biopolymers: Potential platforms for enzyme immobilization

Naturally-derived biopolymers such as alginate, chitosan, cellulose, agarose, guar gum/guaran, agar, carrageenan, gelatin, dextran, xanthan, and pectins, etc. have appealed significant attention over the past several years owing to their natural abundance and availability all over the years, around the globe. In addition, their versatile properties such as non-toxicity, biocompatibility, biodegradability, flexibility, renewability, and the availability of numerous reactive sites offer significant functionalities with multipurpose applications. At present, intensive research efforts have been focused on engineering enzymes using natural biopolymers as novel support/composite materials for diverse applications in biomedical, environmental, pharmaceutical, food and biofuel/energy sectors. Immobilization appears as a straightforward and promising approach to developing biocatalysts with improved catalytic properties as compared to their free counterparts. Biopolymers-assisted enzymes are more stable, robust, and recoverable than that of free forms, and can be employed for continuous biocatalytic reactions. The present review highlights the recent developments and use of biopolymers and their advanced composites as support carriers for the immobilization of a variety of different enzymes to develop biocatalysts with desired catalytic activity and stability characteristics for emerging applications.