Agar-carrageenan hydrogel blend as a carrier for the covalent immobilization of β-D-galactosidase

Biochemical characterization of immobilized recombinant subtilisin and synthesis and functional characterization of recombinant subtilisin capped silver and zinc oxide nanoparticles

This pioneering research explores the transformative potential of recombinant subtilisin, emphasizing its strategic immobilization and nanoparticle synthesis to elevate both stability and therapeutic efficacy. Achieving an impressive 95.25 % immobilization yield with 3 % alginate composed of sodium along with 0.2 M CaCl2 indicates heightened pH levels and thermal resistance, with optimal action around pH 10 as well as 80 °C temperature. Notably, the Ca-alginate-immobilized subtilisin exhibits exceptional storage longevity and recyclability, affirming its practical viability. Comprehensive analyses of the recombinant subtilisin under diverse conditions underscore its adaptability, reflected in kinetic enhancements with increased Vmax (10.7 ± 15 × 103 U/mg) and decreased Km (0.19 ± 0.3 mM) values post-immobilization using N-Suc-F-A-A-F-pNA. UV-visible spectroscopy confirms the successful capping of nanoparticles made of Ag and ZnO by recombinant subtilisin, imparting profound antibacterial efficacy against diverse organisms and compelling antioxidant properties. Cytotoxicity was detected against the MCF-7 breast cancer line of cells, exhibiting IC50 concentrations at 8.87 as well as 14.52 µg/mL of AgNP as well as ZnONP, correspondingly, indicating promising anticancer potential. Rigorous characterization, including FTIR, SEM-EDS, TGA and AFM robustly validate the properties of the capped nanoparticles. Beyond therapeutic implications, the investigation explores industrial applications, revealing the versatility of recombinant subtilisin in dehairing, blood clot dissolution, biosurfactant activity, and blood stain removal. In summary, this research unfolds the exceptional promise of recombinant subtilisin and its nanoparticles, presenting compelling opportunities for diverse therapeutic applications in medicine. These findings contribute substantively to biotechnology and healthcare and stimulate avenues for further innovation and exploration.

Grafting of proteins onto polymeric surfaces: A synthesis and characterization challenge

This review aims at answering the following question: how can a researcher be sure to succeed in grafting a protein onto a polymer surface? Even if protein immobilization on solid supports has been used industrially for a long time, hence enabling natural enzymes to serve as a powerful tool, emergence of new supports such as polymeric surfaces for the development of so-called intelligent materials requires new approaches. In this review, we introduce the challenges in grafting protein on synthetic polymers, mainly because compared to hard surfaces, polymers may be sensitive to various aqueous media, depending on the pH or reductive molecules, or may exhibit state transitions with temperature. Then, the specificity of grafting on synthetic polymers due to difference of chemical functions availability or difference of physical properties are summarized. We present next the various available routes to covalently bond the protein onto the polymeric substrates considering the functional groups coming from the monomers used during polymerization reaction or post-modification of the surfaces. We also focus our review on a major concern of grafting protein, which is avoiding the potential loss of function of the immobilized protein. Meanwhile, this review considers the different methods of characterization used to determine the grafting efficiency but also the behavior of enzymes once grafted. We finally dedicate the last part of this review to industrial application and future prospective, considering the sustainable processes based on green chemistry.

Xylanase covalent binding onto amidated pectin beads: Optimization, thermal, operational and storage stability studies and application

Amidated pectin-polyethylene imine-glutaraldehyde (AP-PEI-GA) immobilizer was prepared. The ideal protocol that should be adopted during the immobilizer preparation was investigated via Box-Behnken design (BBD), and it comprised processing the AP beads with 3.4 % (w/w) PEI solution of pH 9.65 followed by 5.96 % (v/v) GA solution. The obtained AP-PEI-GA immobilizer was efficient, and it acquired 3.03 U.g^-1 of immobilized xylanase (im-xylanase) activity. The computed K_m and V_max values for AP-PEI-GA im-xylanase were 16.67 mg.ml^-1 and 20 g.ml^-1.min^-1, respectively. Through covalent coupling to AP-PEI-GA, Aspergillus niger xylanase thermodynamic properties T_1/2 and D-values were increased by 2.05, 3.08, and 1.35 at 40, 50, and 60 °C, respectively. ΔH_d and ΔG_d for AP-PEI-GA im-xylanase at 40, 50, and 60 °C were higher than those for free form emphasizing more resistance to thermal denaturation. Im-xylanase showed 100 % activity for 20 successive cycles and hydrolyzed different agro-industrial wastes into reducing sugar and xylooligosaccharides (XOS) with more efficiency on pea peel (PP). AP-PEI-GA im-xylanase, PP weight, and hydrolysis time that should be adopted to obtain the highest reducing sugar and XOS yield were optimized through central composite design (CCD). Extracted XOS showed prebiotic and anti-oxidant activities.

Carbohydrate microcapsules tailored and grafted for covalent immobilization of glucose isomerase for pharmaceutical and food industries

Carrageenan is one of the most common carbohydrates utilised in the entrapment industry to immobilise cells and enzymes. However, it lacks functionality. Carrageenan has been grafted to produce fructose by covalently immobilising glucose isomerase (GI). Fructose is one of the most widely used sweeteners in beverages, food production, and the pharmaceutical business. Up to 91.1 U g^-1 gel beads are immobilised by the grafted beads. Immobilized GI has a V_max of 13.8 times that of the free enzyme. pH of immobilized GI was improved from 6.5-7 to 6-7.5 that means more stability in wide pH range. Also, optimum temperature was improved and become 65-75 °C while it was at 70 °C for free enzyme. The immovability and tolerance of the gel beads immobilised with GI over 15 consecutive cycles were demonstrated in a reusability test, with 88 percent of the enzyme's original activity retained, compared to 60 percent by other authors. These findings are encouraging for high-fructose corn syrup producers.

Boosting the stability of β-galactosidase immobilized onto soy-protein isolate-glutaraldehyde-functionalized carrageenan beads

Uncontrolled enzyme-immobilizer interactions were evident after immobilizing β-galactosidase onto soy-protein isolate-glutaraldehyde-functionalized carrageenan beads. Such interactions triggered shortcomings in the immobilized β-galactosidase (iβGL) thermal and storage stabilities. The thermal stability of the iβGL was somewhat lesser than that of the free βGL. Moreover, the iβGL suffered an initial sharp fall-off in its activity after storing it. Thus, approaches were adopted to prevent the occurrence of such uncontrolled enzyme-immobilizer interactions, and accordingly, boost the stability of the iβGL. These approaches involved neutralizing the covalently reactive GA entities via glycine and also altering the functionalizing GA concentrations. Nonetheless, no improvement was recorded in the iβGL thermal stability and this indicated that the uncontrolled enzyme-immobilizer interactions were not mediated via GA. Another approach was then attempted which involved treating the iβGL with lactose. The lactose-treated iβGL (LT-iβGL) presented superior thermal stability as was verified from its smaller k _d and bigger t _1/2 and D-values. The LT-iβGL t _1/2 values were 5.60 and 3.53 fold higher than those presented by the free βGL at 62 and 65 °C, respectively. Moreover, the LT- iβGL presented loftier ΔG than did the free βGL. The storage stability of the LT- iβGL was also superior as it offered 100.41% of its commencing activity on its 43rd storage day. Thus, it could be concluded that lactose prevented the uncontrolled enzyme-immobilizer interactions. Finally, advantageous galacto-oligosaccharides (GOS) were prepared via the iβGL. The GOS were then analyzed with mass spectrometry, and it was shown that their degree of polymerization reached up to 7.

Green method for improving performance attributes of wool fibres using immobilized proteolytic thermozyme

Wool has the tendency to turn into felt during agitation in washing machines. Thus, a benign non-polluting method for the production of machine-washable wool was developed herein. Initially, a proteolytic bacteria was isolated from hot region soil. The bacterial isolate was identified as Bacillus safensis FO-36bMZ836779 according to the 16S rRNA gene sequencing. Afterwards, the extracellular protease produced by this isolate was covalently immobilized in order to enhance its stability under non-ambient conditions which are usually adopted in industrial sectors like textile industries. Sericin, which is usually discharged into degumming effluent of natural silk, was utilized to prepare the immobilization carrier. Box–Behnken design was adopted in order to hone the preparation of the sericin–polyethylene–imine–glutaraldehyde activated agar carrier. The pH and temperature profiles of the free and immobilized proteases were compared. Later, wool fibres were bio-treated with both the free and the immobilized enzymes. The effect of process conditions on the resistance of the bio-finished wool to felting was investigated. The alteration in the fibre morphology was monitored using SEM. Amino acid analysis and alkali solubility tests were adopted to assign any change in the chemical structure of the bio-treated wool. The influence of bio-treatment of wool on its inherent properties was assigned. Results revealed that bio-treatment of wool with the said enzyme led to production of machine-washable wool without severe deterioration in the fibres’ properties. In an energy- and water-consuming process, the hot solution from bio-treatment bath was used successfully in dyeing of wool.

Development of stable agar/carrageenan-Fe3O4-Klebsiella pneumoniae composite beads for efficient phenol degradation

It's of practical importance but highly challenging for cell immobilization supports to maintain mechanical strength and reduce microbial leakage in environmental and industrial applications. Herein, we developed an agar/κ-carrageenan composite hydrogel to entrap Klebsiella pneumoniae with the combination of nano-Fe₃O₄ for processing phenol wastes. The agar/carrageenan-K. pneumoniae composite bead showed good pelletizing properties, superior material strength and high cell loading. Introduction of nano-Fe₃O₄ to the composite gel further enhanced phenol degradation rate by >10% owing to strengthened phenol oxidation by Fe₃O₄-induced hydroxyl radicals (·OH) and improved mass and electron transfers. 50 successive cycles of degradation and recycling using the agar/carrageenan-K. pneumoniae composite bead showed that 1500 mg/L phenol was fully degraded for all cycles with the highest rate of 55.12 mg L^-1·h^-1 obtained at the 15th cycles. The improved stability and recyclability render the as-prepared immobilized phenol-degrading bacteria with great potential for industrial applications.

Bioscouring of wool fibres using immobilized thermophilic lipase

The hydrophobic nature of wool induced by its surface lipid barrier hinders its wettability during processing. Scouring of wool is conducted to remove this lipid barrier and facilitate any wet processes. Scouring of wool is conducted using soda ash followed by rinsing with huge amount of water to ensure complete removal of alkali. This work aimed at utilization of thermophilic lipase enzyme for removal of wool surface lipid barrier without deterioration on the fibre interior. A thermally stable lipase enzyme was produced from thermophilic microorganism; namely Bacillus aryabhattai B8W22, and was utilized in bio-scouring of wool. The produced enzyme was immobilized on sericin-based discs to enhance its stability and to make it reusable. The activity of both free and immobilized lipase enzymes at different conditions was assessed. The effects of bio-scouring of wool on its dyeability with acid, basic, and reactive dyes, as well as on some of its inherent properties, were monitored. Results showed that the bio-scoured wool exhibits enhanced dyeability with the said classes of dyes more than that of conventionally scoured samples. One-bath scouring and dyeing of wool fibres in two successive steps was conducted to reduce consumption of water and energy during wet processing of wool.

Grafted carrageenan: alginate gel beads for catalase enzyme covalent immobilization

A new matrix formulation was devised for catalase immobilization. Carrageenan-alginate beads different ratios were developed and soaked into different ratios of CaCl₂-KCl as a hardening solution. The best formulation for loading capacity was selected, treated with polyethylene imine followed by glutaraldehyde and further studied. The best concentration of catalase for immobilization was 300U/ml and the best loading time was 6 h. The catalytic properties increased after immobilization and the immobilized catalase achieved optimum activity at a temperature range of 30-50 °C that was compared to the optimum activity of free catalase which occurred at 40 °C. Higher catalytic activity of immobilized catalase occurred at alkaline pHs than the free one which achieved optimum catalytic activity at neutral pH. A comparison between the kinetic parameters of immobilized and free catalase showed variation. The K _M and Vmax of the immobilized catalase were 2.4 fold and six times higher than those of free catalase. The results of the study indicate that the formulated matrix can be used as a good matrix for catalase enzyme in various industrial applications.

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100 °C and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70 °C. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Calcium pectinate-agar beads as improved carriers for β-d-galactosidase and their thermodynamics investigation

Polyethyleneimine (PEI) glutaraldehyde-refined calcium pectinate (CaP)-agar beads were presented as improved covalent immobilization matrices. The CaP-agar beads exhibited incremented mechanical stability which facilitated their handling. The beads' concoction and activation processes were honed using the Box-Behnken design which recommended utilizing 5.4% agar, and a 2.95% PEI solution of pH 8.67. The honed CaP-agar beads established a more efficient ionic interaction with PEI which enabled the immobilization of more enzyme while utilizing less PEI than that required to activate the neat CaP beads. Furthermore, the activated CaP-agar beads granted superior operational stability to the immobilized enzyme, β-d-galactosidase (βgal), where it preserved 86.84 ± 0.37% of its precursive activity during its thirteenth reusability round. The CaP-agar immobilized βgal (iβgal) also showed incremented storage stability where it preserved 85.05 ± 3.32% of its precursive activity after 38 days of storage. The thermal stability of the iβgal was shown to be superior to that of the free enzyme as the iβgal exhibited incremented thermodynamic parameters, such as the t _1/2 values, the D values, the thermal denaturation activation energy, the enthalpies, and the Gibb's free energies. The βgal's immobilization onto the activated CaP-agar beads also shifted the enzyme's optimal pH from 4.6-5.1 to 3.3-4.9, whereas its optimal temperature was retained at 55 °C. The procured biocatalyst was exploited to efficiently hydrolyze the lactose in whey permeate.

Impact of immobilization technology in industrial and pharmaceutical applications

The current demands of the world's biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. Compared to free enzymes in solution, immobilized enzymes are more robust and more resistant to environmental changes. More importantly, the heterogeneity of the immobilized enzyme systems allows an easy recovery of both enzymes and products, multiple reuse of enzymes, continuous operation of enzymatic processes, rapid termination of reactions, and greater variety of bioreactor designs. This review summarizes immobilization definition, different immobilization methods, advantages and disadvantages of each method. In addition, it covers some food industries, protein purification, human nutrition, biodiesel production, and textile industry. In these industries, the use of enzymes has become an inevitable processing strategy when a perfect end product is desired. It also can be used in many other important industries including health care and pharmaceuticals applications. One of the best uses of enzymes in the modern life is their application in diagnose and treatment of many disease especially when used in drug delivery system or when used in nanoform.

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.