Covalent immobilization of lipase from Candida rugosa on epoxy-activated cloisite 30B as a new heterofunctional carrier and its application in the synthesis of banana flavor and production of biodiesel

Boosting catalytic efficiency of lipase by regulating amphiphilic microenvironment through reversible addition-fragmentation chain transfer polymerized modifications on polyacrylonitrile fiber

Lipases are increasingly attracting attention in green and sustainable biodiesel production. Currently, the research emphasis lies in immobilizing unstable lipase onto carriers to enhance its performance. Polyacrylonitrile fiber (PANF) is considered to be a promising material for lipase immobilization due to its excellent properties. In this study, functional carriers with regulated surface hydrophobicity were obtained by loading functional groups on PANF via reversible addition-fragmentation chain transfer (RAFT) polymerized modification, and Candida rugosa lipase (CRL) was covalently immobilized on the carrier with glutaraldehyde as a linker. By employing this optimized biocatalyst PANF@BMA&2VImBr-NH2-CRL in the transesterification process, the yield of biodiesel derived from soybean oil reached an impressive 92.7 %. The outstanding performance can be attributed to the activation of lipase interface induced by hydrophobic microenvironment derived from alkyl ester on the carrier skeleton. Moreover, the stability and storage performance of immobilized lipase were significantly improved. The immobilized lipase exhibited facile recovery and maintained a consistent biodiesel yield of 80.9 % even after undergoing 5 cycles of reuse, thereby highlighting its potential for sustainable production. To sum up, our research demonstrates that the designed and prepared process of PANF-supported lipase offers a promising approach for enzyme immobilization, thereby presenting extensive potential applications in the field of biotechnology.

Artificial antibody-antigen-directed immobilization of lipase for consecutive catalytic synthesis of ester: Benzyl acetate case study

A strategy based on artificial antibody-antigen recognition was proposed for the specific directed immobilization of lipase. The artificial antibody was synthesized using catechol as a template, α-methacrylic acid as a functional monomer, and Fe3O4 as the matrix material. Lipase was modified with 3,4-dihydroxybenzaldehyde as an artificial antigen. The artificial antibody can specifically recognize catechol fragment in the enzyme structure to achieve the immobilization of lipase. The immobilization amount, yield, specific activity, and immobilized enzyme activity were 13.2 ± 0.2 mg/g, 78.9 ± 0.4 %, 7.9 ± 0.2 U/mgprotein, and 104.6 ± 1.7 U/gcarrier, respectively. Moreover, the immobilized lipase exhibited strong reusability and regeneration ability. Additionally, the immobilized lipase successfully catalyzed the synthesis of benzyl acetate and demonstrated robust continuous catalytic activity. These results fully demonstrate the feasibility of the proposed artificial antibody-antigen-directed immobilization of lipase.

Fabrication of immobilized lipases from Candida rugosa on hierarchical mesoporous silica for enzymatic enrichment of ω-3 polyunsaturated fatty acids by selective hydrolysis

In this study, lipase from Candida rugosa was immobilized on hydrophobic hierarchical porous hollow silica microsphere (HPHSM-C3) via adsorption. The prepared biocatalyst HPHSM-C3@CRL exhibited higher activity, thermal and pH stability. HPHSM-C3@CRL remained 70.2% of initial activity after 30 days of storage at 24 °C and 50.4% of initial activity after 10 cycles. Moreover, HPHSM-C3@CRL was utilized in enzymatic enrichment of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in glycerides, achieving ω-3 PUFAs content of 53.42% with the hydrolysis rate of 48.78% under optimal condition. The Km and Vmax value of HPHSM-C3@CRL was 42.2% lower and 63.5% higher than those of CRL, respectively. The 3D structure analysis of CRL, substrates and pore structure of HPHSM-C3 suggested that the hierarchical pore improved activity and selectivity of immobilized lipase. This result demonstrated that HPHSM-C3@CRL may be an effective biocatalyst for the enzymatic enrichment of ω-3 PUFAs in food industries.

Advances in surface design and biomedical applications of magnetic nanoparticles

Despite significant efforts by scientists in the development of advanced nanotechnology materials for smart diagnosis devices and drug delivery systems, the success of clinical trials remains largely elusive. In order to address this biomedical challenge, magnetic nanoparticles (MNPs) have gained attention as a promising candidate due to their theranostic properties, which allow the simultaneous treatment and diagnosis of a disease. Moreover, MNPs have advantageous characteristics such as a larger surface area, high surface-to-volume ratio, enhanced mobility, mass transference and, more notably, easy manipulation under external magnetic fields. Besides, certain magnetic particle types based on the magnetite (Fe3O4) phase have already been FDA-approved, demonstrating biocompatible and low toxicity. Typically, surface modification and/or functional group conjugation are required to prevent oxidation and particle aggregation. A wide range of inorganic and organic molecules have been utilized to coat the surface of MNPs, including surfactants, antibodies, synthetic and natural polymers, silica, metals, and various other substances. Furthermore, various strategies have been developed for the synthesis and surface functionalization of MNPs to enhance their colloidal stability, biocompatibility, good response to an external magnetic field, etc. Both uncoated MNPs and those coated with inorganic and organic compounds exhibit versatility, making them suitable for a range of applications such as drug delivery systems (DDS), magnetic hyperthermia, fluorescent biological labels, biodetection and magnetic resonance imaging (MRI). Thus, this review provides an update of recently published MNPs works, providing a current discussion regarding their strategies of synthesis and surface modifications, biomedical applications, and perspectives.

Phenotypic and genetic characterization of a lipolytic Ralstonia mannitolilytica isolate from petroleum-contaminated soil in Iraq

BACKGROUND

Lipases play a crucial role in various industrial applications, and microbial lipases, particularly those from bacteria, possess significant properties. With increasing concerns about the environmental and health impacts of hydrocarbons from pipelines and refineries, there is a growing need to mitigate the risks associated with these compounds.

METHODS

In this study, 40 bacterial isolates were recovered from contaminated soil samples collected from multiple refineries across Iraq. Using the Vitek system, bacterial isolates were identified up to the species level, revealing that only 12 isolates exhibited lipase-producing capabilities.

RESULTS

Among the lipase-producing isolates, Ralstonia mannitolilytica demonstrated the highest extracellular lipase activity, as determined by an olive oil plate assay supplemented with rhodamine B. Confirmation of the species identity was achieved through 16S rRNA gene sequencing, with the obtained sequence deposited under accession number LC772176.1. Further sequence analysis revealed single nucleotide polymorphisms (SNPs) in the genome of Ralstonia mannitolilytica strain H230303-10_N19_7x_R2 (CP011257.1, positions 1,311,102 and 1,311,457). Additionally, the presence of the lipase gene was confirmed through amplification and sequencing using a thermocycler PCR. Sequence analysis of the gene, aligned using Geneious Prime software, identified SNPs (CP010799, CP049132, AY364601, CP011257, and CP023537), and a phylogenetic tree was constructed based on genetic characterization.

CONCLUSION

Our findings highlight the potential of Ralstonia mannitolilytica as a promising candidate for lipase production and contribute to our understanding of its genetic diversity and biotechnological applications in hydrocarbon degradation and industrial processes.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Structure-based modification of a-amylase by conventional and emerging technologies: Comparative study on the secondary structure, activity, thermal stability and amylolysis efficiency

α-Amylase is an endo-enzyme that catalyzes the hydrolysis of starch into shorter oligosaccharides. α-Amylase plays a crucial role in various industries. Manipulated α-amylases are of particular interest due to their remarkable amylolysis efficiency and thermostability for large-scale biotechnological processes. The retained catalytic activity of enzymes is decreased according to extreme pH, temperature, pressure, and chemical reagents. Broad industrial applications of α-amylases need special properties such as stability against temperature, pH, and chelators, and also attain reusability, desirable enzymatic activity, efficiency, and selectivity. Considering the biotechnological importance of α-amylase, its high stability is the most critical challenge for its economic viability. Therefore, improving its functionality and stability recently gained much interest. To achieve this purpose, various emerging technologies in combination with conventional methods on α-Amylases with different sources have been conducted. The present review is an attempt to summarize the effect of various conventional methods and emerging technologies employed to date on α-amylase secondary structure, thermal stability, and performance.

Recent insight into the advances and prospects of microbial lipases and their potential applications in industry

Enzymes play a crucial role in various industrial sectors. These biocatalysts not only ensure sustainability and safety but also enhance process efficiency through their unique specificity. Lipases possess versatility as biocatalysts and find utilization in diverse bioconversion reactions. Presently, microbial lipases are gaining significant focus owing to the rapid progress in enzyme technology and their widespread implementation in multiple industrial procedures. This updated review presents new knowledge about various origins of microbial lipases, such as fungi, bacteria, and yeast. It highlights both the traditional and modern purification methods, including precipitation and chromatographic separation, the immunopurification technique, the reversed micellar system, the aqueous two-phase system (ATPS), and aqueous two-phase flotation (ATPF), moreover, delves into the diverse applications of microbial lipases across several industries, such as food, vitamin esters, textile, detergent, biodiesel, and bioremediation. Furthermore, the present research unveils the obstacles encountered in employing lipase, the patterns observed in lipase engineering, and the application of CRISPR/Cas genome editing technology for altering the genes responsible for lipase production. Additionally, the immobilization of microorganisms' lipases onto various carriers also contributes to enhancing the effectiveness and efficiencies of lipases in terms of their catalytic activities. This is achieved by boosting their resilience to heat and ionic conditions (such as inorganic solvents, high-level pH, and temperature). The process also facilitates the ease of recycling them and enables a more concentrated deposition of the enzyme onto the supporting material. Consequently, these characteristics have demonstrated their suitability for application as biocatalysts in diverse industries.

Improved production of alkaline and solvent-stable proteases from a halotolerant Exiguobacterium isolate through heterologous expression

Halophiles are excellent sources of detergent proteases that are attributed to stability in alkaline pH, salts, surfactants, and hydrophobic solvents. The lower enzymatic yields and tedious downstream processes necessitate the search for newer halophilic sources. We have previously reported a halotolerant Exiguobacterium sp. TBG-PICH-001, which secretes solvent-tolerant alkaline protease/s. The present study describes the heterologous expression of two protease genes, namely, rsep metalloprotease (WP_195864791, 1.23 Kb) and tpa serine protease (WP_195864453, 0.879 Kb) genes. These were cloned into the pET 22b + plasmid vector and expressed in Escherichia coli BL21(DE3). The recombinant proteases rsep and tpa showed respective yields of 6.3 and 6.7 IU/mg, 11 and 12-fold higher than the crude native protease/s from TBG-PICH-001. These showed soluble expression at 46 and 32 KDa, respectively. These were purified to homogeneity through Ni-NTA-affinity chromatography. The purified proteases were characterized for properties like pH & temperature optima and stability, substrate specificity, kinetic parameters, and detergent attributes. They showed affinity towards various substrates with a respective Km of 392 and 301 μM towards casein. The recombinant proteases exhibited stability in the alkaline pH (7-10), surfactants, metal ions, detergents, and hydrophobic solvents, rendering their suitability as detergent additives.

Dynamic immobilization of bacterial cells on biofilm in a polyester nonwoven chemostat

Cell immobilization plays an important role in biocatalysis for high-value products. It is necessary to maintain the viability of immobilized cells for bioconversion using viable cells as biocatalysts. In this study, a novel polyester nonwoven chemostat was designed for cell immobilization to investigate biofilm formation and the dynamic balance between adsorption and desorption of cells on polyester nonwoven. The polyester nonwoven was suitable for cell immobilization, and the cell numbers on the polyester nonwoven can reach 6.5 ± 0.38 log CFU/mL. After adding the polyester nonwoven to the chemostat, the fluctuation phenomenon of free bacterial cells occurred. The reason for this phenomenon was the balance between adsorption and desorption of bacterial cells on the polyester nonwoven. Bacterial cells could adhere to the surface of polyester nonwoven via secreting extracellular polymeric substances (EPS) to form biofilms. As the maturation of biofilms, some dead cells inside the biofilms can cause the detachment of biofilms. This process of continuous adsorption and desorption of cells can ensure that the polyester nonwoven chemostat has lasting biological activity.

Tuning surface interactions on MgFe2O4 nanoparticles to induce interfacial hyperactivation in Candida rugosa lipase immobilization

Lipase adsorption on solid supports can be mediated by a precise balance of electrostatic and hydrophobic interactions. A suitable fine-tuning could allow the immobilized enzyme to display high catalytic activity. The objective of this work was to investigate how pH and ionic strength fluctuations affected protein-support interactions during immobilization via physical adsorption of a Candida rugosa lipase (CRL) on MgFe2O5. The highest amount of immobilized protein (IP) was measured at pH 4, and an ionic strength of 90 mM. However, these immobilization conditions did not register the highest hydrolytic activity (HA) in the biocatalyst (CRLa@MgFe2O4), finding the best values also at acidic pH but with a slight shift towards higher values of ionic strength around 110 mM. These findings were confirmed when the adsorption isotherms were examined under different immobilization conditions so that the maximum measurements of IP did not coincide with that of HA. Furthermore, when the recovered activity was examined, a strong interfacial hyperactivation of the lipase was detected towards acidic pH and highly charged surrounding environments. Spectroscopic studies, as well as in silico molecular docking analyses, revealed a considerable involvement of surface hydrophobic protein-carrier interactions, with aromatic aminoacids, especially phenylalanine residues, playing an important role. In light of these findings, this study significantly contributes to the body of knowledge and a better understanding of the factors that influence the lipase immobilization process on magnetic inorganic oxide nanoparticle surfaces.

Complexation of Boronic Acid with Chiral α-Hydroxycarboxylic Acids and the Ability of the Complexes to Catalyze α-Hydroxycarboxylic Acid Esterification

The complexation of boric acid (BA) with various α-hydroxycarboxylic acids (HCAs) was examined by analyzing the change in the optical rotation after the addition of BA to aqueous HCA solutions, and the catalytic properties of the complexes were examined by catalyzing the esterification of the HCAs. The absolute values of the optical rotation of the HCAs increased with increasing BA-to-HCA molar ratio, and the rate of change of the optical rotation gradually decreased as the BA-to-HCA molar ratio increased, reaching a minimum value at a molar ratio of approximately three. As a catalyst, BA could catalyze the acetylation of hydroxyl groups in addition to the esterification of HCAs. Compared to the conventional synthesis routes of ATBC and ATOC, a synthesis route with BA as the catalyst allowed for a lower frequency of catalyst separation and replacement while providing light-colored products. BA could catalyze the formation of triethyl citrate, and the yield of triethyl citrate reached 93.8%. BA could also catalyze the reaction between malic acid and pinene to produce borneol malate. After saponification of borneol malate, borneol was obtained with a yield of 39%.

Enzyme immobilization technology as a tool to innovate in the production of biofuels: A special review of the Cross-Linked Enzyme Aggregates (CLEAs) strategy

This review emphasizes the crucial role of enzyme immobilization technology in advancing the production of two main biofuels, ethanol and biodiesel, with a specific focus on the Cross-linked Enzyme Aggregates (CLEAs) strategy. This method of immobilization has gained attention due to its simplicity and affordability, as it does not initially require a solid support. CLEAs synthesis protocol includes two steps: enzyme precipitation and cross-linking of aggregates using bifunctional agents. We conducted a thorough search for papers detailing the synthesis of CLEAs utilizing amylases, cellulases, and hemicellulases. These key enzymes are involved in breaking down starch or lignocellulosic materials to produce ethanol, both in first and second-generation processes. CLEAs of lipases were included as these enzymes play a crucial role in the enzymatic process of biodiesel production. However, when dealing with large or diverse substrates such as lignocellulosic materials for ethanol production and oils/fats for biodiesel production, the use of individual enzymes may not be the most efficient method. Instead, a system that utilizes a blend of enzymes may prove to be more effective. To innovate in the production of biofuels (ethanol and biodiesel), enzyme co-immobilization using different enzyme species to produce Combi-CLEAs is a promising trend.

Carboxylic acid reductases: Structure, catalytic requirements, and applications in biotechnology

Biocatalysts have been gaining extra attention in recent decades due to their industrial-relevance properties, which may hasten the transition to a cleaner environment. Carboxylic acid reductases (CARs) are large, multi-domain proteins that can catalyze the reduction of carboxylic acids to corresponding aldehydes, with the presence of adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). This biocatalytic reaction is of great interest due to the abundance of carboxylic acids in nature and the ability of CAR to convert carboxylic acids to a wide range of aldehydes essentially needed as end products such as vanillin or reaction intermediates for several compounds production such as alcohols, alkanes, and amines. This modular enzyme, found in bacteria and fungi, demands an activation via post-translational modification by the phosphopantetheinyl transferase (PPTase). Recent advances in the characterization and structural studies of CARs revealed valuable information about the enzymes' dynamics, mechanisms, and unique features. In this comprehensive review, we summarize the previous findings on the phylogeny, structural and mechanistic insight of the domains, post-translational modification requirement, strategies for the cofactors regeneration, the extensively broad aldehyde-related industrial application properties of CARs, as well as their recent immobilization approaches.

Recent advances in simultaneous thermostability-activity improvement of industrial enzymes through structure modification

Engineered thermostable microbial enzymes are widely employed to catalyze chemical reactions in numerous industrial sectors. Although high thermostability is a prerequisite of industrial applications, enzyme activity is usually sacrificed during thermostability improvement. Therefore, it is vital to select the common and compatible strategies between thermostability and activity improvement to reduce mutants̕ libraries and screening time. Three functional protein engineering approaches, including directed evolution, rational design, and semi-rational design, are employed to manipulate protein structure on a genetic basis. From a structural standpoint, integrative strategies such as increasing substrate affinity; introducing electrostatic interaction; removing steric hindrance; increasing flexibility of the active site; N- and C-terminal engineering; and increasing intramolecular and intermolecular hydrophobic interactions are well-known to improve simultaneous activity and thermostability. The current review aims to analyze relevant strategies to improve thermostability and activity simultaneously to circumvent the thermostability and activity trade-off of industrial enzymes.

Solvent tolerant enzymes in extremophiles: Adaptations and applications

Non-aqueous enzymology has always drawn attention due to the wide range of unique possibilities in biocatalysis. In general, the enzymes do not or insignificantly catalyze substrate in the presence of solvents. This is due to the interfering interactions of the solvents between enzyme and water molecules at the interface. Therefore, information about solvent-stable enzymes is scarce. Yet, solvent-stable enzymes prove quite valuable in the present day biotechnology. The enzymatic hydrolysis of the substrates in solvents synthesizes commercially valuable products, such as peptides, esters, and other transesterification products. Extremophiles, the most valuable yet not extensively explored candidates, can be an excellent source to investigate this avenue. Due to inherent structural attributes, many extremozymes can catalyze and maintain stability in organic solvents. In the present review, we aim to consolidate information about the solvent-stable enzymes from various extremophilic microorganisms. Further, it would be interesting to learn about the mechanism adapted by these microorganisms to sustain solvent stress. Various approaches to protein engineering are used to enhance catalytic flexibility and stability and broaden biocatalysis's prospects under non-aqueous conditions. It also describes strategies to achieve optimal immobilization with minimum inhibition of the catalysis. The proposed review would significantly aid our understanding of non-aqueous enzymology.

Cefotaxime degradation by the coupled binary CdS-PbS: characterization and the photocatalytic process kinetics

Increased water pollution due to discharging industrial/urban/hospital wastewater has been adopted to introduce/develop novel removal techniques/catalyst/adsorbent. The hexagonal (wurtzite) CdS and the cubic PbS nanoparticles (NPs) were synthesized, coupled, and supported onto clinoptilolite NPs (CNP). Then, the sample was characterized by X-ray powder diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FTIR), and a scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX) techniques. The average crystallite size for CdS NPs, PbS NPs, CNP, and CdS-PbS/CNP samples was obtained at about 24, 36, 27, and 14 nm using the Scherrer formula value of nanometer, by the W-H formula, 31, 17, 39, and 51, respectively. Only a detectable slope can be observed from the DRS spectra for CdS NPs at 591 nm corresponding to an Eg value of 2.1 eV. PbS NPs have a broad abruption peak that begins from the visible region and extends to the IR region of the light. A boosted photocatalytic activity of the supported binary catalysts towards cefotaxime (CT) was reached. An apparent first kinetic model was reached with a k-value of 0.021 min^-1 corresponding to the t_1/2 value of 33 min. A decreased COD trend for the photodegraded CT solutions was reached, and the chemical oxygen demand (COD) results in the Hinshelwood model showed a k-value of 0.016 min^-1, corresponding to a t_1/2 value of 43 min.

Performance of Microenvironment-induced Lipase Immobilization on diversify Surface of Magnetic Particle

The orientation of the enzyme molecular on the interface of the carrier affects its activity. Therefore, it is very important to controllably induce the orientation of the enzyme on the surface to improve the performance of the immobilized enzyme. Magnetic nanoparticles were used to construct microenvironments with the different surface hydrophobicity and charge characteristics by controlled modification, and those particles with various microenvironments were further used to study their interaction with the lipase. The amount and activity of immobilized enzyme on different magnetic nanoparticles surfaces were studied by physical adsorption and covalent binding. Through the enzyme surface and particle surface characteristics analysis, the possible preferred orientation of enzyme and enzyme conformation on different surfaces were inferred, which well explained the effect of surface induction on enzyme loading and activity. The methods of surface microenvironment regulation and the strategy of controllable induction of enzyme orientation adopted in this study are enlightening for the rational design of immobilized enzyme methods.

Covalent immobilization of lipase on an ionic liquid-functionalized magnetic Cu-based metal-organic framework with boosted catalytic performance in flavor ester synthesis

Enzymatic esterification plays an important role in the fields of chemistry and biotechnology. In this study, lipase was immobilized on an ionic liquid (IL)-modified magnetic metal-organic framework (MOF) and used to synthesize isoamyl acetate. The immobilized lipase (PPL-ILs/Fe₃O₄@MOF) showed 2.1-fold and 1.8-fold higher activity compared to the free and immobilized lipase without ILs (PPL-Fe₃O₄@MOF), respectively. In addition, the anti-denaturant ability and reusability of the PPL-ILs/Fe₃O₄@MOF were also higher than those of other samples. The ester yield reached 75.1% when the biocatalyst was used to synthesize isoamyl acetate in hexane. The synthesized supports supplied a good microenvironment for the immobilized lipase through multiple interactions. Results of the structural analysis showed that the conformation state of lipase molecules changed after immobilization. The magnetism of the prepared biocatalyst makes it easy to recycle so that PPL-ILs/Fe₃O₄@MOF maintained 70.2% of the initial activity after eight cycles. The prepared composite materials exhibited good potential in lipase immobilization with enhanced catalytic ability and stability.

Preparation of new hydrogels by visible light cross-linking of dextran methacrylate and poly(ethylene glycol)-maleic acid copolymer

In this work, a series of new biodegradable and biocompatible hydrogels were synthesized by photopolymerization of dextran-methacrylate (DXM) with poly(ethylene glycol)-maleic acid copolymer (poly(PEG-co-MA, PEGMA)) using (-)-riboflavin as a visible light photoinitiator and L-arginine as a co-photoinitiator. DXM was prepared by acylation of dextran (DX) with methacryloyl chloride (MAC), and PEGMA was synthesized by polycondensation of poly(ethylene glycol) (PEG) and maleic acid (MA). The DXM and PEGMA were characterized by FT-IR and ¹HNMR spectroscopy. Different types of hydrogels from various ratios of DXM and PEGMA were prepared and characterized by SEM. The results showed that the prepared hydrogel by photo-cross-linking of DXM (DPHG0) was transparent and flexible, and its physical shape was excellent, but it was sticky. The stickiness was reduced by increasing the PEGMA contents, and different types of DXM/PEGMA hydrogels (DPHG1-4) with various properties were prepared. For example, DPHG2 (PEGMA content was 0.25 g) was transparent and flexible, its physical shape was excellent, and it was not sticky. The prepared hydrogels showed excellent cytocompatibility, and their tensile and compressive strength were also evaluated. Additionally, the in vitro degradation and swelling ratios of the prepared hydrogels were studied in buffer solution at different pHs.

The boosted photocatalytic effects of a zeolite supported CdS towards an antibiotic model pollutant: a brief kinetics study

In recent decades, increased world population and industrial activities explosively polluted our environment, especially the aquatic resources. This requires introducing/developing novel methods to decrease the pollution extent of such resources. Here, the hexagonal (wurtzite) CdS nanoparticles (NPs) were synthesized and supported onto ball-mill prepared clinoptilolite NPs (CNP). Samples were briefly characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope equipped with an energy dispersive X-ray analyzer (SEM-EDX), and diffuse reflectance spectroscopy (DRS) techniques. The average crystallite size for CdS NPs and CdS-CNP samples was estimated to be about 9.0 nm and 12.3 nm (from the Scherrer formula) and about 19.7 and 17.5 nm (from the Williamson-Hall model), respectively. From the DRS spectra, the absorption wavelengths of 595 and 546 nm correspond to band gap energies of 2.08, and 2.27 eV was obtained for CdS NPs and CdS-CNP samples. The samples were then used in the photodegradation of cefotaxime (CT), and the results showed a boosted photocatalytic activity for CdS-CNP rather than CdS NPs. The photodegradation process obeyed the pseudo-first-order kinetic model, and the CdS and CdS-CNP catalysts obtained the k-values of 0.013 min^-1 and 0.023 min^-1. When the photodegraded CT solutions were used in COD experiments, the k-values changed to 0.011 min^-1 and 0.029 min^-1, respectively. The zeolite support is an eco-friendly natural zeolite with abundant deposits in Iran that yields a cost-effective method.

A core/shell TiO2 magnetized molecularly imprinted photocatalyst (MMIP@TiO2): synthesis and its photodegradation activity towards sulfasalazine

Although the selectivity of TiO₂ for the degradation of target molecules is not enough, it is a broadly employed photocatalyst for the degradation of many pollutants. Molecularly imprinted compounds owing to their extreme recognition specificity have become increasingly popular for preparing selective photocatalysts. In this work, based on molecularly imprinted magnetized TiO₂ (MMIP@TiO₂), a selective photocatalyst was prepared. Via the co-precipitation method, Fe₃O₄ particles were prepared and coated respectively by SiO₂, vinyl end groups, and molecularly imprinted polymers (MIP). The synthesized photocatalyst was characterized by the X-ray diffraction method (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive x-ray spectrometry (EDX), vibrating sample magnetometry (VSM), high-performance liquid chromatography (HPLC), and photoluminescence analysis (PL). The photocatalyst was then used to degrade the sulfasalazine pharmaceutical pollutant under UV irradiation. An average crystallite size of 9 nm was obtained for the MMIP@TiO₂ sample from the Scherrer formula and 34.5 nm by the Williamson-Hall formula. The results revealed that compared to the non-imprinted counterpart, the molecularly imprinted photocatalyst had significantly higher efficiency and selectivity for the degradation of target molecules. The process was forwarded with 90% efficiency within 10 min. Optimal conditions were 10.0 min irradiation when 25 mL SSZ solution (50 mg/L), 0.07 g/L catalyst dose, and pH 6.0 were applied. The maximum removal efficiency was calculated to be 92%. The external magnetic field quickly removed the photocatalyst from the solution and regenerated it. It was revealed that after each regeneration cycle, the efficiency dropped. Nevertheless, 63% of the preliminary effectiveness remained after four regeneration steps.

Industrial applications of fungal lipases: a review

Fungal lipases (triacylglycerol acyl hydrolases EC 3.1.1.3) are significant industrial enzymes and have several applications in a number of industries and fields. Fungal lipases are found in several species of fungi and yeast. These enzymes are carboxylic acid esterases, categorized under the serine hydrolase family, and do not require any cofactor during the catalyzing of the reactions. It was also noticed that processes including the extraction and purification of lipases from fungi are comparatively easier and cheaper than other sources of lipases. In addition, fungal lipases have been classified into three chief classes, namely, GX, GGGX, and Y. Fungal lipases have applications not only in the hydrolysis of fats and oils (triglycerides) but are also involved in synthetic reactions such as esterification, acidolysis, alcoholysis, interesterification, and aminolysis. The production and activity of fungal lipases are highly affected by the carbon source, nitrogen source, temperature, pH, metal ions, surfactants, and moisture content. Therefore, fungal lipases have several industrial and biotechnological applications in many fields such as biodiesel production, ester synthesis, production of biodegradable biopolymers, formulations of cosmetics and personal care products, detergent manufacturing, degreasing of leather, pulp and paper production, textile industry, biosensor development, and drug formulations and as a diagnostic tool in the medical sector, biodegradation of esters, and bioremediation of wastewater. The immobilization of fungal lipases onto different carriers also helps in improving the catalytic activities and efficiencies of lipases by increasing thermal and ionic stability (in organic solvents, high pH, and temperature), being easy to recycle, and inducing the volume-specific loading of the enzyme onto the support, and thus, these features have proved to be appropriate for use as biocatalysts in different sectors.

Kinetic and thermodynamic studies of novel acid phosphatase isolated and purified from Carthamus oxyacantha seedlings

Acid phosphatase (ACP) is a key enzyme in the regulation of phosphate feeding in plants. In this study, a new ACP from C. oxyacantha was isolated to homogeneity and biochemically described for the first time. Specific activity (283 nkat/mg) was found after 2573 times purification fold and (17 %) yield. Using SDS-PAGE under denaturing and nondenaturing conditions, ACP was isolated as a monomer with a molecular weight of 36 kDa. LC-MS/MS confirmed the presence of this band, suggesting that C. oxycantha ACP is a monomer. The enzyme could also hydrolyze orthophosphate monoester with an optimal pH of 5.0 and a temperature of 50 °C. Thermodynamic parameters were also determined (Ea, ΔH°, ΔG°, and ΔS°). ACP activity was further studied in the presence of cysteine, DTT, SDS, EDTA, β-ME, Triton-X-100 H₂O₂, and PMSF. The enzyme had a K_m of 0.167 mM and an Ea of 9 kcal/mol for p-nitrophenyl phosphate. The biochemical properties of the C. oxyacantha enzyme distinguish it from other plant acid phosphatases and give a basic understanding of ACP in C. oxyacantha. The results of this investigation also advance our knowledge about the biochemical significance of ACP in C. oxyacantha. Thermal stability over a wide pH and temperature range make it more suitable for use in harsh industrial environments. However, further structural and physiological studies are anticipated to completely comprehend its important aspects in oxyacantha species.

A Z-scheme CdS/BiVO4 photocatalysis towards Eriochrome black T: An experimental design and mechanism study

The synergistic photocatalytic activity was obtained when CdS and BiVO₄ nanoparticles (NPs) were coupled. The samples were characterized by XRD, FTIR, SEM-EDX, and UV-DRS techniques, and their pHpzc was also estimated. The crystallite size of the coupled sample was estimated at 37.3 and 12.5 nm by the Scherrer and Williamson-Hall equations, respectively. The band gaps and the potential positions of VB and CB levels of the semiconductors used were determined. The highest boosted photocatalytic activity was obtained when the CdS: BiVO₄ mole ratio was 1:1. RSM studied the simultaneous interactions between the selected variables, and the model F-value of 110.61> F_{0.05, 14, 13} = 2.4 accompanied by the LOF F-value of 5.20 < F_{0.05, 10, 3} = 8.79 confirm the model significance. The correlation coefficients of R² = 0.9861, the adjusted R² = 0.9710, and the predicted R² = 0.9417, also establish a satisfactory model for processing the experimental data. In the scavenging agent study, photodegradation mechanisms were suggested; among them, the direct Z-scheme mechanism is more favorable for illustrating the EBT-photodegradation by the binary CdS-BiVO₄ photocatalyst. The proposed system, especially the direct Z-scheme mechanism, is suitable as a potential hydrogen production system.

Immobilization and Application of the Recombinant Xylanase GH10 of Malbranchea pulchella in the Production of Xylooligosaccharides from Hydrothermal Liquor of the Eucalyptus (Eucalyptus grandis) Wood Chips

Xylooligosaccharides (XOS) are widely used in the food industry as prebiotic components. XOS with high purity are required for practical prebiotic function and other biological benefits, such as antioxidant and inflammatory properties. In this work, we immobilized the recombinant endo-1,4-β-xylanase of Malbranchea pulchella (MpXyn10) in various chemical supports and evaluated its potential to produce xylooligosaccharides (XOS) from hydrothermal liquor of eucalyptus wood chips. Values >90% of immobilization yields were achieved from amino-activated supports for 120 min. The highest recovery values were found on Purolite (142%) and MANAE-MpXyn10 (137%) derivatives, which maintained more than 90% residual activity for 24 h at 70 °C, while the free-MpXyn10 maintained only 11%. In addition, active MpXyn10 derivatives were stable in the range of pH 4.0−6.0 and the presence of the furfural and HMF compounds. MpXyn10 derivatives were tested to produce XOS from xylan of various sources. Maximum values were observed for birchwood xylan at 8.6 mg mL−1 and wheat arabinoxylan at 8.9 mg mL−1, using Purolite-MpXyn10. Its derivative was also successfully applied in the hydrolysis of soluble xylan present in hydrothermal liquor, with 0.9 mg mL−1 of XOS after 3 h at 50 °C. This derivative maintained more than 80% XOS yield after six cycles of the assay. The results obtained provide a basis for the application of immobilized MpXyn10 to produce XOS with high purity and other high-value-added products in the lignocellulosic biorefinery field.

Presenting B-DNA as macromolecular crowding agent to improve efficacy of cytochrome c under various stresses

Existence of numerous biomolecules results in biological fluids to be extremely crowded. Thus, Macromolecular crowding is an essential phenomenon to sustain active conformation of proteins in biological systems. Herein, double helical deoxyribonucleic acid (B-DNA) is presented for the first time as a biomacromolecular crowding system for sustainable packaging of cytochrome c (Cyt C). The peroxidase activity of Cyt C was investigated in the presence of various concentrations of B-DNA (from salmon milt). At an optimized concentration of 0.125 mg/mL B-DNA, an 11-fold higher catalytic activity was found than in native Cyt C with improved stability. Molecular docking and spectroscopic analyses revealed that electrostatic and H-bonding are the main interactions between DNA and Cyt C that affect the structural stability and activity of the protein. Moreover, the catalytic activity and stability of the protein were further investigated in the presence of severe process conditions by UV-visible, circular dichroism, and Fourier-transform infrared spectroscopies. Molecularly crowded Cyt C showed significantly higher activity and stability under severe environments such as high temperature (110 °C), oxidative stress, high pH (pH 10) and biological (trypsin) and chemical denaturants (urea) compared to bare Cyt C. The observed results support the suitability of DNA-based macromolecular crowding media as a viable and effective stabilizer of proteins against multiple stresses.

Producing Natural Flavours from Isoamyl Alcohol and Fusel Oil by Using Immobilised Rhizopus oryzae Lipase

Enzymatic synthesis of short-chain esters (flavours) might enable their labelling as natural, increasing their value. Covalently immobilised Rhizopus oryzae lipase (EO-proROL) was used to synthesise isoamyl butyrate and acetate. In cyclohexane, the best performer reaction solvent, 1.8 times higher yield of isoamyl butyrate (ca. 100%) than isoamyl acetate (ca. 55%) was obtained. Optimum initial acid concentration (410 mM) and acid:alcohol mole ratio (0.5) were established by a central composite rotatable design to maximise isoamyl butyrate single-batch and cumulative production with reused enzyme. These conditions were used to scale up the esterification (150 mL) and to assess yield, initial esterification rate, productivity and enzyme operational stability. Commercial isoamyl alcohol and fusel oil results were found to be similar as regards yield (91% vs. 84%), initial reaction rate (5.4 µM min−1 with both substrates), operational stability (40% activity loss after five runs with both) and productivity (31.09 vs. 28.7 mM h−1). EO-proROL specificity for the structural isomers of isoamyl alcohol was also evaluated. Thus, a successful biocatalyst and product conditions ready to be used for isoamyl ester industrial production are here proposed.

Characterization of a thermostable, protease-tolerant inhibitor of α-glycosidase from carrot: A potential oral additive for treatment of diabetes

Inhibiting α-glucosidase activity is important in controlling postprandial hyperglycemia and, thus, helping to manage type-2 diabetes mellitus (T2DM). In the present study, we purified a hypothetical protein of carrots called DCHP (Daucus Carrot hypoglycemic peptide), and their inhibitory effects on α-glucosidase, as well as related mechanisms, were investigated. The recombinant DCHP protein with a molecular weight of 8 kDa showed strong inhibitory activity against α-glycosidase and maintained good stability in solution. DCHP exhibited no inhibitory activity but was tolerant to trypsin and chymotrypsin. Cellular experiments demonstrated that glucose consumption and lactic acid production increased rapidly when treated with DCHP in Caco-2 and HepG2 cells. DCHP crystal was generated, and the crystal structure, which was similar to that of rBTI and consisted of a central α-helix and a two-stranded β-sheet with a unique loop region. The interaction between DCHP and α-glycosidase was investigated by molecular docking and site-directed mutation, which revealed that Glu43, Pro46, Thr47 Thr48 and Gln49 are the key residues in DCHP that inhibit α-glycosidase activity. This work provides potential bioactive peptides as functional foods or nutraceutical supplements in preventing and managing T2DM.

A designed experiment for CdS-AgBr photocatalyst toward methylene blue

A boosted photocatalytic activity was observed for the CdS-AgBr nanocomposite in the degradation of methylene blue (MB). The experimental design method based on the response surface methodology (RSM) approach used to study the simultaneous interaction effects between the influencing variables. Analysis of variance (ANOVA) of the results confirmed a significant model for processing the data because an F value of 32.34 for the suggested model was higher than that of the critical value of F_{0.05, 14, 13} = 2.55 at 95% confidence interval. This analysis also showed a non-significant lack of fit (LOF) (as a measure of the randomness of the deviations around the obtained data) because the LOF F value of 8.27 was smaller than that of the critical value of F_{0.05, 10, 3} = 8.79. R² values near to unity were achieved (the multiple correlation coefficients R² (R² = 0.9627), adjusted R² (adj-R² = 0.9226), and predicted R² (pred-R² = 0.7423)). Six center points suggested by the model included the following conditions: pH, 6.1; C_MB, 3.5 mg/L; a dose of the catalyst, 0.68 g/L; and irradiation time, 40.5 min. During the center point runs, the degradation efficiencies were obtained in the range of 38 to 43%. The optimal run included pH, 9; catalyst dosage, 1 g/L; irradiation time, 60 min; and C_MB, 2 mg/L, and the best removal efficiency of 98% was achieved during these conditions.

Effect of polyol osmolytes on the structure-function integrity and aggregation propensity of catalase: A comprehensive study based on spectroscopic and molecular dynamic simulation measurements

Owing to the ability of catalase to function under oxidative stress vis-à-vis its industrial importance, the structure-function integrity of the enzyme is of prime concern. In the present study, polyols (glycerol, sorbitol, sucrose, xylitol), were evaluated for their ability to modulate structure, activity and aggregation of catalase using in vitro and in silico approaches. All polyols increased catalase activity by decreasing K_m and increasing V_max resulting in enhanced catalytic efficiency (k_cat/K_m) of the enzyme, with glycerol being the most efficient with a k_cat/K_m increase from 4.38 × 10⁴ mM^-1 S^-1 (control) to 5.8 × 10⁵ mM^-1 S^-1. Correlatively with this, enhanced secondary structure with reduced hydrophobic exposure was observed in all polyols. Furthermore, increased stability, with an increase in melting temperature by 15.2 °C, and almost no aggregation was observed in glycerol. Overall, ability to regulate structure-function integrity and aggregation propensity was highest for glycerol and lowest for xylitol. Simulation studies were performed involving structural dynamics measurements, principal component analysis and free energy landscape analysis. Altogether, all polyols were stabilizing in nature and glycerol, in particular, has potential to efficiently prevent not only the antioxidant defense system but also might serve as a stability aid during industrial processing of catalase.

Efficient hydrolysis of starch by α-amylase immobilized on cloisite 30B and modified forms of cloisite 30B by adsorption and covalent methods

In this paper, α-amylase from Bacillus subtilis was successfully immobilized on three supports. First, α-amylase was immobilized on cloisite 30B via the adsorption method. Then cloisite 30B was activated with tosyl chloride and epichlorohydrin. These activated supports were used for covalent immobilization of α-amylase, and their enzymatic activities were effectively tested in the starch hydrolysis. The results demonstrated that the specific activity of α-amylase immobilized on cloisite 30B was 2.39 ± 0.03, for α-amylase immobilized on activated cloisite 30B with epichlorohydrin was 1.96 ± 0.05 and for α-amylase immobilized on activated cloisite 30B with tosyl chloride was 2.17 ± 0.05 U mg^-1. The optimum pH for the activity of free α-amylase was 7, but for α-amylase immobilized on cloisite 30B was 8, and for α-amylase immobilized on activated supports was 7.5. The immobilized enzymes had better thermal resistance and storage stability than free α-amylase, and they also showed excellent reusability.

Fabrication of lipase-loaded particles by coacervation with chitosan

Coacervation of the lipase from Aspergillus oryzae (AOL) with chitosan was a feasible way to fabricate lipase-loaded particles and the optimum conditions were phase separation pH 5.5, chitosan to AOL mass ratio 1:5, and temperature 25 °C in the absence of NaCl, which conferred an AOL loading efficiency of up to 95.48% and activity recovery of 69.60%. The AOL-chitosan coacervates were highly porous and more susceptible to weight loss upon heating. Coacervation with chitosan increased the activity of AOL and shifted its optimum pH from 7.0 to 6.0, but exerted no effect on its optimum temperature (45 °C). Thermal deactivation kinetics analysis revealed that the coacervated AOL was more thermal stable, while the Michaelis-Menten kinetics analysis indicated that coacervation with chitosan increased the V_max of AOL by 2.4 folds, but decreased its substrate affinity by 3.6 folds. Hence, the AOL-chitosan coacervates are potential in the construction of Pickering emulsion-based lipase catalysis systems.

Preparation and characterization of stable core/shell Fe3O4@Au decorated with an amine group for immobilization of lipase by covalent attachment

The self-assembly approach was used for amine decoration of core/shell Fe₃O₄@Au with 4-aminothiophenol. This structure was used for covalent immobilization of lipase using a Ugi 4-component reaction. The amine group on the structure and carboxylic group from lipase can react in the Ugi reaction and a firm and stable covalent bond is created between enzyme and support. The synthesized structure was fully characterized and its activity was explored in different situations. The results showed the pH and temperature stability of immobilized lipase compared to free lipase in a wide range of pH and temperature. Also after 60 days, it showed excellent activity while residual activity for the free enzyme was only 10%. The synthesized structure was conveniently separated using an external magnetic field and reused 6 times without losing the activity of the immobilized enzyme.

The self-assembly approach was used for amine decoration of core/shell Fe₃O₄@Au with 4-aminothiophenol.

Enhancing thermostabilization of a newly discovered α-amylase from Bacillus cereus GL96 by combining computer-aided directed evolution and site-directed mutagenesis

This study has described the characterization of a new a-amylase from the recently isolated Bacillus cereus GL96. Subsequently, an in-silico approach was taken into account to redesign the enzyme to meet higher thermal stability. Finally, the engineered enzyme was constructed experimentally using side-directed mutagenesis (SDM) and characterized accordingly. The enzyme was stable over pH 4-11, with the highest activity at 9.5. The temperature profile of the wild-type enzyme showed optimum activity at 50 °C plus 40% of stability at temperatures up to 70 °C. The in-silico result was indicated D162W, D162R, and D162K as the three stabilizing mutations. Among them, D162K showed better results, especially in the molecular dynamics simulation, and therefore, it was constructed by SDM. This variant was shown 5 °C higher optimum temperature (55 °C) with increasing activity than the native enzyme. In addition, it was significantly more stable than the native form. For example, while the latter almost wholly lost its function at a temperature above 70 °C, the D162K can retain more than 40% of its initial activity up to 80 °C. Considering the promising properties that the mutant enzyme showed, it can be considered for further investigation to meet the industrial requirement completely.

Production of a recyclable nanobiocatalyst to synthesize quinazolinone derivatives

Nanobiocatalysts (NBCs) are an emerging innovation that paves the way toward sustainable and eco-friendly endeavors.

Smart chemistry of enzyme immobilization using various support matrices - A review

The surface chemistry, pendent functional entities, and ease in tunability of various materials play a central role in properly coordinating with enzymes for immobilization purposes. Due to the interplay between the new wave of support matrices and enzymes, the development of robust biocatalytic constructs via protein engineering expands the practical scope and tunable catalysis functions. The concept of stabilization via functional entities manipulation, the surface that comprises functional groups, such as thiol, aldehyde, carboxylic, amine, and epoxy have been the important driving force for immobilizing purposes. Enzyme immobilization using multi-functional supports has become a powerful norm and presents noteworthy characteristics, such as selectivity, specificity, stability, resistivity, induce activity, reaction efficacy, multi-usability, high catalytic turnover, optimal yield, ease in recovery, and cost-effectiveness. There is a plethora of literature on traditional immobilization approaches, e.g., intramolecular chemical (covalent) attachment, adsorption, encapsulation, entrapment, and cross-linking. However, the existing literature is lacking state-of-the-art smart chemistry of immobilization. This review is a focused attempt to cover the literature gap of surface functional entities that interplay between support materials at large and enzyme of interest, in particular, to tailor robust biocatalysts to fulfill the growing and contemporary needs of several industrial sectors.