Optimization of immobilization conditions of Bacillus atrophaeus FSHM2 lipase on maleic copolymer coated amine-modified graphene oxide nanosheets and its application for valeric acid esterification

Advancements in enzyme immobilization on magnetic nanomaterials: toward sustainable industrial applications

Enzymes are widely used in biofuels, food, and pharmaceuticals. The immobilization of enzymes on solid supports, particularly magnetic nanomaterials, enhances their stability and catalytic activity. Magnetic nanomaterials are chosen for their versatility, large surface area, and superparamagnetic properties, which allow for easy separation and reuse in industrial processes. Researchers focus on the synthesis of appropriate nanomaterials tailored for specific purposes. Immobilization protocols are predefined and adapted to both enzymes and support requirements for optimal efficiency. This review provides a detailed exploration of the application of magnetic nanomaterials in enzyme immobilization protocols. It covers methods, challenges, advantages, and future perspectives, starting with general aspects of magnetic nanomaterials, their synthesis, and applications as matrices for solid enzyme stabilization. The discussion then delves into existing enzymatic immobilization methods on magnetic nanomaterials, highlighting advantages, challenges, and potential applications. Further sections explore the industrial use of various enzymes immobilized on these materials, the development of enzyme-based bioreactors, and prospects for these biocatalysts. In summary, this review provides a concise comparison of the use of magnetic nanomaterials for enzyme stabilization, highlighting potential industrial applications and contributing to manufacturing optimization.

An Appraisal on Prominent Industrial and Biotechnological Applications of Bacterial Lipases

Microbial lipases expedite the hydrolysis and synthesis of long-chain acyl esters. They are highly significant commercial biocatalysts to biotechnologists and organic chemists. The market size of lipase is anticipated to reach $590 million by 2023. This is all owing to their versatility in properties, including stability in organic solvents, interfacial activation in micro-aqueous environments, high substrate specificity, and activity in even non-aqueous milieu. Lipases are omnipresent and synthesized by various living organisms, including animals, plants, and microorganisms. Microbial lipases are the preferred choice for industrial applications as they entail low production costs, higher yield independent of seasonal changes, easier purification practices, and are capable of being genetically modified. Microbial lipases are employed in several common industries, namely various food manufactories (dairy, bakery, flavor, and aroma enhancement, etc.), leather tanneries, paper and pulp, textiles, detergents, cosmetics, pharmaceuticals, biodiesel synthesis, bioremediation and waste treatment, and many more. In recent decades, circumspection toward eco-friendly and sustainable energy has led scientists to develop industrial mechanisms with lesser waste/effluent generation, minimal overall energy usage, and biocatalysts that can be synthesized using renewable, low-cost, and unconventional raw materials. However, there are still issues regarding the commercial use of lipases which make industrialists wary and sometimes even switch back to chemical catalysis. Industrially relevant lipase properties must be further optimized, analyzed, and explored to ensure their continuous successful utilization. This review comprehensively describes the general background, structural characteristics, classifications, thermostability, and various roles of bacterial lipases in important industries.

The response surface methodology for optimization of Halomonas sp. C2SS100 lipase immobilization onto CaCO3 for treatment of tuna wash processing wastewater

An immobilized enzyme could exhibit selectively modified physicochemical properties, and it might offer a better environment for the enzyme activity. In this study, the immobilization yield of crude Halomonas sp. lipase was optimized to improve its stability. Thanks to its high adsorption capacity, CaCO₃ has been chosen as support for the immobilization process. Furthermore, response surface methodology (RSM) was used to determine optimal conditions for the immobilization of the bacterial lipase. Five tested factors (enzyme solution, support amount, time, temperature, and acetone volume) were optimized applying a central composite design of RSM. The maximum yield of lipase immobilization was improved to 96%. Furthermore, a biochemical characterization proved a significant improvement of the immobilized lipase stability. The immobilized enzyme is more stable at extreme pH values and high temperatures than the free one. We also tested the reusability of the immobilized lipase by evaluating the recovery of the support using simple filtration. Thanks to its high stability, the immobilized lipase was invested in an effective treatment of tuna wash processing wastewater. The oil biodegradation efficiency was established at 81.5% and was confirmed by Fourier transformation infrared spectrometry. Likewise, the biological oxygen demand values were reduced which makes a possible reduction of the wastewater pollution degree.

Hydroxyapatite/Glycyrrhizin/Lithium-Based Metal-Organic Framework (HA/GL/Li-MOF) Nanocomposite as Support for Immobilization of Thermomyces lanuginosus Lipase

The hydroxyapatite/glycyrrhizin/lithium-based metal-organic framework (HA/GL/Li-MOF) nanocomposites were synthesized via the hydrothermal method in the presence of lecithin and glycyrrhizin. Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) were applied for characterization of the fabricated nanocomposites. The HA/GL/Li-MOF and Li-MOF nanocomposites were employed as support for immobilization of Thermomyces lanuginosus lipase (TLL). The Plackett-Burman and Box-Behnken designs were used for screening and optimizing of variables affecting the immobilization conditions, respectively. The optimum specific activity of immobilized TLL on HA/GL/Li-MOF and Li-MOF nanocomposites (41.8 ± 1.2 U/mg and 39.4 ± 3.1 U/mg, respectively) was predictably determined at support concentration of 0.5 mg/mL, glutaraldehyde concentration of 5 mM, and enzyme activity of 20 U/mg, while the specific activities of TLL@ HA/GL/Li-MOF and TLL@Li-MOF were experimentally found to be 39.5 ± 3.7 U/mg and 38.5 ± 2.3 U/mg, respectively. The stability results showed that the TLL@ HA/GL/Li-MOF has suitable stability against pH and thermal denaturation. However, the immobilized TLL on Li-MOF represented lower stability compared with that of the HA/GL/Li-MOF. The immobilized TLL on HA/GL/Li-MOF maintained near 70% of its original activity after 15 days' storage and during 5 runs of application. In addition, TLL@HA/GL/Li-MOF exhibited higher enzyme-substrate affinity (K_m, 10.1 mM) compared to that of TLL@Li-MOF (K_m, 23.4 mM). Therefore, these findings demonstrated the potential use of HA/GL/Li-MOF nanocomposites for enzyme immobilization.

Magnetic casein aggregates as an innovative support platform for laccase immobilization and bioremoval of crystal violet

In this study, casein@CoFe₂O₄ was fabricated through a green synthesis methodology and applied to immobilize laccase. The constructed casein@CoFe₂O₄ exhibited porous structures with distinct cavities and suitable magnetic properties. The abundance of aromatic functional groups on the surface renneted casein and possible π-type interaction between laccase and para-κ-casein resulted in a successful immobilization. The biocatalyst retained 50% of its initial activity after 24 reusability cycles, indicating stable immobilization of laccase onto the casein microstructures. The stability of laccase after immobilization was improved by 300% in comparison with the free enzyme, especially in basic pH values. The constructed laccase@casein@CoFe₂O₄ was then incorporated to remove crystal violet (CV) as an environmentally harmful synthetic tri-phenylmethane dye. The prepared heterogeneous biocatalyst effectively diminished the antimicrobial activity of CV up to 81.3% in 40 min against some bacterial strains, resulting from the formation of more minor toxic metabolites identified by liquid chromatography coupled with mass spectroscopy after degradation procedure. The proposed green and feasible method for the preparation of magnetic casein aggregates has not been previously reported. The incorporation of casein, which acted as a molecular chaperon, resulted in a significant improvement in the enzymatic stability and exhibited appropriate reusability for the constructed biocatalytic system.

Application of a constrained mixture design for lipase production by Penicillium roqueforti ATCC 10110 under solid-state fermentation and using agro-industrial wastes as substrate

Solid state fermentation (SSF) simulates the natural conditions fungal growth, where the amount of water in the reaction medium must be restricted, thus limiting the use of liquid substrate. An analytical strategy to deal with this limitation is the design of blending with constraints. Thus, the objective of the work was to optimize two constrained waste mixtures for the production of lipase by Penicillium roqueforti ATCC 10110 under SSF, using different substrates that combine solid and liquid waste. For this, the best fermentation time was determined through a fermentative profile, afterwards a restricted-mix design with lower and upper limits of the components of mixture I (cocoa residue, solid palm oil residue and liquid palm oil residue) and II (cocoa residue, mango residue and palm oil residue liquid palm) was applied. By means of Pareto and contour graphs, the maximum production points of lipase in mixtures I (6.67 ± 0.34 U g^-1) and II (6.87 ± 0.35 U g^-1) were obtained. The restricted mixture design proved to be a promising tool in the production of lipase by P. roqueforti ATCC 10110 under SSF since the use of restrictions is useful when intending to combine solid and liquid residues in fermentation processes.

Immobilization of Candida rugosa lipase on magnetic chitosan beads and application in flavor esters synthesis

In this work, magnetic chitosan (MCH) beads were synthesized by phase-inversion method, and grafted with polydopamine (PDA) and then used for direct immobilization of Candida rugosa lipase by Schiff base reaction. The amount of immobilized enzyme and the retained activity were found to be 47.3 mg/g and 72.8%, respectively, at pH 7.0, and at 25 °C. The apparent Km (9.7 mmol/L), and Vmax (384 U/mg) values of the immobilized lipase were significantly changed compared to the free lipase. The MCH@PDA-lipase was better thermal and storage stability at different temperatures than those of the free lipase. In hexane medium, the esterification reaction results showed that the maximum conversions of isoamylalcohol and isopentyl alcohol to isoamyl acetate and isopentyl acetate using the MCH@PDA-lipase were found to be 98.4 ± 1.3% and 73.7 ± 0.7%, respectively. These results showed that the MCH@PDA-lipase can be used as an operative immobilized enzyme system for many biotechnological applications.

Immobilization of lipase on β-cyclodextrin grafted and aminopropyl-functionalized chitosan/Fe3O4 magnetic nanocomposites: An innovative approach to fruity flavor esters esterification

The lipase from Bacillus licheniformis NCU CS-5 was immobilized onto β-cyclodextrin (CD) grafted and aminopropyl-functionalized chitosan-coated Fe₃O₄ magnetic nanocomposites (Fe₃O₄-CTS-APTES-GA-β-CD). Fourier transform infrared spectroscopy, thermogravimetry analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed that not only the functionalized magnetic nanoparticles were synthesized but also the immobilized lipase was successfully produced. The immobilized lipase exhibited higher optimal pH value (10.5) and temperature (60℃) than the free lipase. The pH and thermal stabilities of the immobilized lipase were improved significantly compared to the free lipase. The immobilized lipase remained more than 80% of the relative activity at temperature of 60 ℃ and pH 12.0. The immobilized lipase also remained over 80% of its relative activity after 28 days of storage and 15 cycles of application. The application of the immobilized lipase in esterification of isoamyl acetate and pentyl valerate showed that maximum esterification efficiency was achieved in n-hexane having 68.0% and 89.2% respectively. Therefore, these results indicated that the Fe₃O₄-CTS-APTES-GA-β-CD nanoparticles are novel carriers for immobilizing enzyme, and the immobilized lipase can be used as an innovative green approach to the synthesis of fruity flavor esters in food industry.

Improved adenylate cyclase activity via affinity immobilization onto co-modified GO with bio-inspired adhesive and PEI

Adenylate cyclase (AC) can efficiently catalyze the conversion of adenosine triphosphate (ATP) to cyclic adenosine-3', 5'-monophosphate (cAMP). However, AC directly immobilized on substrate is not desirable due to enzyme inactivation. Herein, bio-inspired adhesive of polydopamine and polyethyleneimine (PDA/PEI) was used as flexible chains to graft on graphene oxide (GO), and the AC was directionally immobilized through affinity between metal ions and his-tags of AC. The properties of modified GO and the activity of immobilized AC were studied in detail. PDA/PEI layers have been proved to improve the amino density of GO surface for affinity groups decoration and adjust the interaction between AC and support. And modified GO by this novel method contributes to subsequent grafting and immobilization of AC by affinity. AC immobilized on modified GO exhibited high activity recovery with about 90 % of free AC, while enzyme immobilized on unmodified GO has been inactivated. This study offers a versatile approach for support modification and enzyme oriented immobilization. PDA/PEI functionalized GO can be used as a promising carrier to immobilize other his-tagged enzymes.

Optimization of immobilization of Pseudomonas cepacia lipase on multiwalled carbon nanotubes functionalized with glycyrrhizin and Tween 80

In the present study, multiwalled carbon nanotubes (MWCNTs) were functionalized with glycyrrhizin and Tween 80 and applied for immobilization of Pseudomonas cepacia lipase (PcL). Characterization of f-MWCNTs was performed through Fourier-transform infrared spectroscopy, thermal gravimetric, field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis. The optimum specific activity of immobilized PcL (studied by Plackett-Burman statistical design) occurred at 0.3 mg/mL of f-MWCNTs, 25 mM of phosphate buffer (pH 6.0), 15 min sonication time, 8 U/mL of enzyme concentration, and 24 h immobilization time at 4 °C in the absence of glutaraldehyde. In these conditions, the specific activity was 16.57 ± 0.71 U/mg, which was very close to the predicted amount (16.62 ± 0.64 U/mg). The results of thermal and pH stability showed that the stability of immobilized PcL was higher than that of the free PcL. The activity of immobilized PcL on f-MWCNTs held 93% after being incubated for 60 min at 70 °C. Moreover, the immobilized PcL on f-MWCNTs retained about 65% of its initial activity after 30 days of storage at 25 °C. In addition, about 50% of initial activity of immobilized PcL retained after 10 cycles of uses. Therefore, f-MWCNTs could be introduced as suitable support for enzymes immobilization.

Evaluation of biological activities, structural and conformational properties of bovine beta- and alpha-trypsin isoforms in aqueous-organic media

The study of the biological activity of trypsin isoforms in aqueous-organic media is of great interest to various fields of knowledge and biochemistry applications. Thus enzymatic, structural, and energetic properties of bovine β- and α-trypsin isoforms were compared in aqueous-organic media using 30 mg of each isoform. The results showed that the changes induced on the structure and activity of the same trypsin isoform occur at different concentrations. Better results for activity (ionic strength of 0.11 mol·L^-1, at 37 °C and pH 8.0) were found in 0-40% of ethanolic media in which the activity for β-trypsin was about 60% higher than ɑ-trypsin. The ethanolic system does not cause significant changes in the level of secondary structure but the β-trypsin isoform undergoes a major rearrangement. The use of until 60% (v/v) ethanol showed that β-trypsin presents a denaturation process 17% more cooperative. The organic solvent causes redistribution in the supramolecular arrangement of both isoforms: all concentrations used induced the β-trypsin molecules to rearrange into agglomerates. The ɑ-trypsin rearranges into agglomerates up to 60% (v/v) of ethanol and aggregates at 80% (v/v) of ethanol. Both isoforms keep the enzymatic activity up to 60% (v/v) of ethanol.

Immobilized lipases-based nano-biocatalytic systems - A versatile platform with incredible biotechnological potential

Lipases belong to α/β hydrolases that cause hydrolytic catalysis of triacylglycerols to release monoacylglycerols, diacylglycerols, and glycerol with free fatty acids. Lipases have a common active site that contains three amino acid residues in a conserved Gly-X-Ser-X-Gly motif: a nucleophilic serine residue, an acidic aspartic or glutamic acid residue, and a basic histidine residue. Lipase plays a significant role in numerous industrial and biotechnological processes, including paper, food, oleochemical and pharmaceutical applications. However, its instability and aqueous solubility make application expensive and relatively challenging. Immobilization has been considered as a promising approach to improve enzyme stability, reusability, and survival under extreme temperature and pH environments. Innumerable supporting material in the form of natural polymers and nanostructured materials is a crucial aspect in the procedure of lipase immobilization used to afford biocompatibility, stability in physio-chemical belongings, and profuse binding positions for enzymes. This review outlines the unique structural and functional properties of a large number of polymers and nanomaterials as robust support matrices for lipase immobilization. Given these supporting materials, the applications of immobilized lipases in different industries, such as biodiesel production, polymer synthesis, additives, detergent, textile, and food industry are also discussed.

Characterization of a novel lipase from Bacillus licheniformis NCU CS-5 for applications in detergent industry and biodegradation of 2,4-D butyl ester

Enzymatic degradation has become the most promising approach to degrading organic ester compounds. In this study, Bacillus licheniformis NCU CS-5 was isolated from the spoilage of Cinnamomum camphora seed kernel, and its extracellular lipase was purified, with a specific activity of 192.98 U/mg. The lipase was found to be a trimeric protein as it showed a single band of 27 kDa in SDS-PAGE and 81 kDa in Native-PAGE. It was active in a wide range of temperatures (5-55 °C) and pH values (6.0-9.0), and the optimal temperature and pH value were 40 °C and 8.0, respectively. The enzyme was active in the presence of various organic solvents, metal ions, inhibitors and surfactants. Both crude and purified lipase retained more than 80% activity after 5 h in the presence of commercial detergents, suggesting its great application potential in detergent industry. The highest activity was found to be towards medium- and long-chain fatty acids (C₆-C₁₈). Peptide mass spectrometric analysis of the purified lipase showed similarity to the lipase family of B. licheniformis. Furthermore, it degraded more than 90% 2,4-D butyl ester to its hydrolysate 2,4-D within 24 h, indicating that the novel lipase may be applied to degrade organic ester pesticides.

Immobilization of enzymes on nanoinorganic support materials: An update

Despite the widespread use in various industries, enzyme's instability and non-reusability limit their applications which can be overcome by immobilization. The nature of the enzyme's support material and method of immobilization affect activity, stability, and kinetics properties of enzymes. Here, we report a comparative study of the effects of inorganic support materials on immobilized enzymes. Accordingly, immobilization of enzymes on nanoinorganic support materials significantly improved thermal and pH stability. Furthermore, immobilizations of enzymes on the materials mainly increased K_m values while decreased the V_max values of enzymes. Immobilized enzymes on nanoinorganic support materials showed the increase in ΔG value, and decrease in both ΔH and ΔS values. In contrast to weak physical adsorption immobilization, covalently-bound and multipoint-attached immobilized enzymes do not release from the support surface to contaminate the product and thus the cost is decreased while the product quality is increased. Nevertheless, nanomaterials can enter the environment and increase health and environmental risks and should be used cautiously. Altogether, it can be predicated that hybrid support materials, directed immobilization methods, site-directed mutagenesis, recombinant fusion protein technology, green nanomaterials and trailor-made supports will be used increasingly to produce more efficient immobilized industrial enzymes in near future.