Rhizomucor Miehei Research Articles

Synthesis and microencapsulation of acylglycerols rich in omega-3 PUFAs by glycerolysis using lipase immobilized on activated carbon

This work aimed to explore the potential of immobilized lipase (Rhizomucor miehei) on activated carbon to convert the high Free Fatty Acid (FFA) content of squid waste oil into acylglycerols (Mono-diacylglycerols (MDG)) rich in n-3 PUFAs in a solvent-free system. The product was microencapsulated by complex coacervation, and stability studies were investigated. The effect of glycerolysis conditions was evaluated according to enzyme concentration, derivative (immobilized lipase) concentration, substrate molar ratio, and reaction time, with the conversion of Free Fatty Acid as the response variable. The optimal parameters were 15 mg g−1 support, 8 % of derivative (w/v of the reaction mixture), 1:5 of glycerol:oil, and 24 h. The lipid class of squid waste oil in the optimal conditions was Ethyl ester (EE) = 2.63 %, Triacylglycerol (TAG) = 17.91 %, FFA = 8.08 %, and MDG = 71.38 %. The fatty acid composition analysis confirmed that squid waste oil had a high content of omega-3 PUFAs (ω-3 = 42.28 %). The enzyme-treated oil was microencapsulated through complex coacervation to protect the oil against oxidation. Microscope and Scanning Electron Microscopy (SEM) confirmed the microcapsule formation. The microcapsules showed unexpectedly high oxidative stability (OSI = 52.35 h) compared to untreated (OSI = 0.04 h) and lipase-treated oil (OSI = 2.46 h). Therefore, immobilized lipase on activated carbon has the potential to efficiently synthesize acylglycerol without solvents, making it a fast and reusable enzyme technology for creating omega-3-rich functional ingredients. Furthermore, microencapsulation by complex coacervation can stabilize the omega-3 oil structure against oxidation for food and pharmaceutical distribution.

Phenolic Content, Antioxidant and Antimicrobial Properties of Hawthorn (Crataegus orientalis) Fruit Extracts Obtained via Carbohydrase-Assisted Extraction

The enzyme-assisted approaches for plant phenolics extraction are more eco-friendly methods compared to acid or alkaline hydrolysis. Carbohydrase enzymes can release free phenolics from plant materials by cleaving the glycosidic bonds between phenolic compounds and cell wall polymers. In this study, the efficiency of carbohydrase-assisted treatment approaches was evaluated to extract bioactive phenolics from hawthorn (Crataegus orientalis) fruit residues. Enzymatic treatment of the fruits was operated by using a crude cellulolytic enzyme cocktail from Rhizomucor miehei NRRL 5282 and a pectinase preparate from Aspergillus niger. Both cellulase and combined cellulase–pectinase treatments improved the total phenolic content (TPC) and antioxidant activity of extracts. The TPC increased to 1899 ± 27 mg gallic acid equivalents/100 g dry matter during the combined enzyme treatment, showing a strong correlation with the average antioxidant capacity determined by ferric-reducing antioxidant power (1.7-fold increment) and 2,2-diphenyl-1-picrylhydrazyl (1.15-fold increment) reagents. The major phenolics in enzyme-treated extracts were vanillic and ferulic acids, the concentrations of which increased 115.6-fold and 93.9-fold, respectively, during carbohydrase treatment. The planktonic growth of Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Chromobacterium violaceum was slightly inhibited by the extracts with minimum inhibitory concentration values between 15.0 and 77.9 mg/mL, while the yeasts tested were quite resistant to the samples. B. subtilis and yeast biofilms were sensitive to the enzyme-treated extracts, which also showed quorum-sensing inhibitory effects against C. violaceum. The obtained bioactive hawthorn extracts hold potential as a natural source of antioxidants and antimicrobials.

Development of a Novel Support Modification for Efficient Lipase Immobilization: Preparation, Characterization, and Application for Bio-flavor Production

The low cost and excellent catalytic properties of lipase for industrial processes are highly desirable. A promising new approach involves the support modification of lipase and spacer arm, which enables the enhancement of lipase properties. This study investigates the immobilization of crude lipase from Mucor miehei onto a Polyurethane Foam (PUF) surface using various coating techniques. The PUF matrix was obtained through isocyanate and polyol reactions. Subsequently, the PUF was coated by adsorbing lipase and adding edible support material. The immobilized lipase was then utilized in the hydrolysis of coconut oil to produce fatty acids. Furthermore, the immobilized enzyme was employed in the esterification of fatty acids to produce bio-flavors. The results demonstrate that the attachment reaction using support material, namely lecithin, gelatin, MgCl2, and Polyethylene glycol 6000 (PEG), all of which are simple and edible, was able to enhance the stability and reusability of lipase. This immobilization technique increased triglyceride hydrolysis into FFA by 422%. The successful edible support modification of immobilized lipase from M. miehei on PUF, coupled with significantly enhanced enzyme stability and catalytic activity, offers a promising, environmentally friendly solution for diverse applications in the food industry. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enzymatic Transesterification Using Different Immobilized Lipases and its Biodiesel Effect on Gas Emission

Biodiesel, a third-generation bio-fuels, offering several advantages over regular diesel fuel. Waste cooking oil (WCO) emerges as an ideal feedstock due to its availability and easy accessibility. In this work, biodiesel is utilized from two different types of immobilized lipases: Rhizomucor miehei lipase (RMIM) and Candida antarctica lipase B (CALB). The impact of the molar ratio of oil to methyl acetate (1:3-1:12) was evaluated for both lipases, and the resultant biodiesel was tested in diesel engine. The enzymatic transesterification was carried out in ultrasonic assistance and the results showed that the greatest yield of 81.20% at 45℃, using CALB as a biocatalyst, 1.8% (w/v) lipase and oil to methyl acetate molar ratio of 1:12 within 3 hours. Triacetin, by-product was determined their concentration for each molar ratio and analyzed using FTIR range of 500cm-1 to 4000cm-1, revealing a significant absorption peak at 1238.90cm-1. Biodiesel was blended with commercial diesel fuel in varying quantities of 7, 10, and 20% by volume (B20). The results were compared to Industrial Diesel Fuel 7% (B7) and Commercial Diesel Fuel 10% (B10). NOx and CO2 emission drops as the percentage of diesel/biodiesel blends increases, supporting WCO as a cost-effective biodiesel feedstock with low petrol pollution.

The production and biological activity of fungal chitosan from the mycelial waste of Rhizomucor miehei

In this study, waste biomass of industrial enzyme producer Rhizomucor miehei was used as an alternative source for fungal chitosan production. Fungal chitosan was obtained from mycelial waste at the deproteinization and deacetylation stages at different temperatures and times of alkali and acid treatment with different concentrations of sodium hydroxide (1–3 N) and acetic acid (2–4 %), respectively. High chitosan yield (70.6 mg/g) was reached at the optimized conditions when the concentration of NaOH (3 N), the deproteinization time (20 mins) and temperature ( 95℃), the concentration of acetic acid (4 %), the deacetylation time (6 hrs) and temperature (85℃). The fungal chitosan with a molecular weight of 14 kDa showed a deacetylation degree of 78 %. The XRD pattern showed two peaks at 2θ values of 9° and 19°. The antimicrobial activity of the fungal chitosan showed broad spectrum at low concentrations (125–250 µg/mL) against the test microorganisms. As wound healing activity, after five days post-scratching, the HaCaT cells cultured in the presence of fungal chitosan demonstrated a notable 57 % increase in migration rate. These findings underscored the efficacy of the produced fungal chitosan, highlighting its promising biological activities. This is the first report to evaluate the use of waste Rhizomucor miehei biomass as alternative source for chitosan.

Substrate specificity of commercial lipases activated by a hydration–aggregation pretreatment in anhydrous esterification reactions

Substrate specificity in non-aqueous esterification catalyzed by commercial lipases activated by hydration–aggregation pretreatment was investigated. Four microbial lipases from Rhizopus japonicus, Burkholderia cepacia, Rhizomucor miehei, and Candida antarctica (fraction B) were used to study the effect of the carbon chain length of saturated fatty acid substrates on the esterification activity with methanol in n-hexane. Hydration–aggregation pretreatment had an activation effect on all lipases used, and different chain length dependencies of esterification activity for lipases from different origins were demonstrated. The effects of various acidic substrates with different degrees of unsaturation, aromatic rings, and alcohol substrates with different carbon chain lengths on esterification activity were examined using R. japonicus lipase, which demonstrated the most remarkable activity enhancement after hydration–aggregation pretreatment. Furthermore, in the esterification of myristic acid with methanol catalyzed by the hydrated–aggregated R. japonicus lipase, maximum reaction rate (5.43 × 10−5 mmol/(mg-biocat min)) and Michaelis constants for each substrate (48.5 mM for myristic acid, 24.7 mM for methanol) were determined by kinetic analysis based on the two-substrate Michaelis-Menten model.

Clinical features of pediatric mucormycosis: role of metagenomic next generation sequencing in diagnosis.

Mucormycosis is an uncommon invasive fungal infection that has a high mortality rate in patients with severe underlying diseases, which leads to immunosuppression. Due to its rarity, determining the incidence and optimal treatment methods for mucormycosis in children is challenging. Metagenomic next-generation sequencing (mNGS) is a rapid, precise and sensitive method for pathogen detection, which helps in the early diagnosis and intervention of mucormycosis in children. In order to increase pediatricians' understanding of this disease, we conducted a study on the clinical features of mucormycosis in children and assessed the role of mNGS in its diagnosis. We retrospectively summarized the clinical data of 14 children with mucormycosis treated at the First Affiliated Hospital of Zhengzhou University from January 2020 to September 2023. Of the 14 cases, 11 case of mucormycosis were classified as probable, and 3 cases were proven as mucormycosis. Most children (85.71%) had high-risk factors for mucormycosis. All 14 children had lung involvement, with 5 cases of extrapulmonary dissemination. Among the 14 cases, 4 cases underwent histopathological examination of mediastinum, lung tissue or kidney tissue, in which fungal pathogens were identified in 3 patients. Fungal hyphae was identified in 3 cases of mucormycosis, but only 1 case yielded a positive culture result. All patients underwent mNGS testing with samples from blood (8/14), bronchoalveolar lavage fluid (6/14), and tissue (1/14). mNGS detected fungi in all cases: 7 cases had Rhizomucor pusillus, 4 cases had Rhizopus oryzae, 3 cases had Rhizopus microsporus, 1 case had Lichtheimia ramosa, and 1 case had Rhizomucor miehei. Coinfections were found with Aspergillus in 3 cases, bacteria in 3 cases, and viruses in 5 cases. Children with mucormycosis commonly exhibit non-specific symptoms like fever and cough during the initial stages. Early diagnosis based on clinical symptoms and imaging is crucial in children suspected of having mucormycosis. mNGS, as a supplementary diagnostic method, offers greater sensitivity and shorter detection time compared to traditional mucormycosis culture or histopathological testing. Additionally, mNGS enables simultaneous detection of bacteria and viruses, facilitating timely and appropriate administration of antibiotics and thereby enhancing patient outcomes.

A Whole-Process Visible Strategy for the Preparation of Rhizomucor miehei Lipase with Escherichia coli Secretion Expression System and the Immobilization.

Rhizomucor miehei (RM) lipase is a regioselective lipase widely used in food, pharmaceutical and biofuel industries. However, the high cost and low purity of the commercial RM lipase limit its industrial applications. Therefore, it is necessary to develop cost-effective strategies for large-scale preparation of this lipase. The present study explored the high-level expression of RM lipase using superfolder green fluorescent protein (sfGFP)-mediated Escherichia coli secretion system. The sfGFP(-15) mutant was fused to the C-terminus of RM lipase to mediate its secretion expression. The yield of the fusion protein reached approximately 5.1g/L with high-density fermentation in 5-L fermentors. Unlike conventional secretion expression methods, only a small portion of the target protein was secreted into the cell culture while majority of the fusion protein was still remained in the cytoplasm. However, in contrast to intracellular expression, the target protein in the cytoplasm could be transported efficiently to the supernatant through a simple washing step with equal volume of phosphate saline (PBS), without causing cell disruption. Hence, the approach facilitated the downstream purification step of the recombinant RM lipase. Moreover, contamination or decline of the engineered strain and degradation or deactivation of the target enzyme can be detected efficiently because they exhibited bright green fluorescence. Next, the target protein was immobilized with anion-exchange and macropore resins. Diethylaminoethyl sepharose(DEAE), a weak-basic anion-exchange resin, exhibited the highest bind capacity but inhibited the activity of RM lipase dramatically. On the contrary, RM lipase fixed with macropore resin D101 demonstrated the highest specific activity. Although immobilization with D101 didn't improve the activity of the enzyme, the thermostability of the immobilized enzyme elevated significantly. The immobilized RM lipase retained approximately 90% of its activity after 3-h incubation at 80°C. Therefore, D101 was chosen as the supporting material of the target protein. The present study established a highly efficient strategy for large-scale preparation of RM lipase. This innovative technique not only provides high-purity RM lipase at a low cost but also has great potential as a platform for the preparation of lipases in the future.

Obtaining a biodegradable biocatalyst – study on lipase immobilization on spent coffee grounds as potential carriers

Coffee waste can be reused as matrices for enzyme immobilization, as it contains various organic compounds able to adsorb catalytic proteins. In this study, spent coffee grounds were used as a support in the immobilization process in their native form and after being pretreated with hexane, ethanol, and sulphuric acid solution, respectively. Microbial lipases from Aspergillus oryzae, Thermomyces lanuginosus, and Rhizomucor miehei were adsorbed on the carrier, and as a reference, the abovementioned lipases were also immobilized on a synthetic matrix - Lewatit VP OC 1600. The research investigated the impact of the purification step on the immobilization process and the full characteristics of the obtained biocatalysts. The hydrolytic and synthetic activities of the immobilized enzyme preparations were tested, as well as substrate specificity, recovery, and temperature and pH activity profiles. SEM and FTIR analyses were also performed. The results showed that the chemical composition of coffee waste influenced the activity of the obtained biocatalysts, and the lack of hemicellulose caused a reduction in lipolytic activity. The study reveals that spent coffee grounds can be a potential support for enzyme immobilization, and lipases adsorbed on them have improved properties such as hydrolytic or synthetic activity, and stability in pH.

The role of microbial coagulants on the physicochemical, proteolysis, microstructure and sensory properties of low-fat Edam cheese manufactured from ultrafiltered buffalo milk

This work investigates the influence of using microbial coagulants, including Rhizomucor miehei (MCR) protease and Cryphonectria parasitica (MCC) protease, on the quality characteristics of low-fat Edam cheese made from ultrafiltered buffalo milk (LFUE). Concurrently, a benchmark with calf rennet (CR) has been also performed. Throughout a 90-day ripening period, the cheeses were assessed for their physicochemical features, proteolysis, texture, free amino acid and free fatty acid content, microstructure, and sensory attributes. The study revealed that both microbial coagulants had no significant impact on the physicochemical composition and firmness of the cheeses while slightly affected the free fatty acids. Cheeses made with microbial coagulants displayed higher proteolysis, with MCR and MCC cheeses exhibiting greater levels of water-soluble nitrogen and 12% trichloroacetic acid-soluble nitrogen than CR cheese. MCR and MCC cheeses exhibited more extensive breakdown of αs- and β-caseins, as indicated by the SDS-PAGE electrophoretogram, compared to CR cheese during ripening. As for the proteolytic activity, the microbial coagulant contributed to shaping the free amino acid content, microstructure, and sensory qualities of the cheeses. Notably, MCC cheese outperformed MCR or CR cheeses in terms of free amino acid levels. MCR and MCC cheeses resulted in smooth microstructures with uniform protein networks as observed by microscopy, while CR cheese displayed rough, granular surfaces. With the highest scores for appearance, body, texture, and flavor, MCC cheese demonstrated superior sensory properties compared with MCR and CR cheeses.

Rhamnopyranoside Pivaloyl Esters as Black and White Fungus Inhibitors: Molecular Docking, Dynamics and ADMET Analysis

The "Black and White Fungus" is a very infrequently developing pathogen with a high fatality rate that has prompted widespread public health concern during the period of the COVID-19 pandemic. This pathogenic fungus may be widely distributed in nature, in plants, and in deteriorating fruits and vegetables because of its widespread nature. Numerous sugar molecules, such as glucopyranoside and glucofuranose, have been reported to have significant antibacterial, antifungal, and antiviral activity, and they were also revealed to be able to inhibit multidrug-resistant microorganisms. The recent black fungus epidemic was extremely serious in India, combined with COVID-19, which contributed to the high mortality impact and deterioration of the situation due to the unavailability of effective treatments. So, rhamnopyranose type derivatives 1–9 were studied against the proteins associated with black and white fungi such as Mycolicibacterium smegmatis (PDB ID 7D6X), Rhizomucor miehei (PDB ID 4WTP), Candida auris (PDB ID 6U8J), and Aspergillus luchuensis (PDB 1BK1). These compounds exhibited favorable physical and biochemical scores, as well as appropriate ADMET metrics, among other characteristics. Following the molecular docking procedure, it was found that 1–9 had the highest binding affinity in most cases, (> -6.00 kcal/mol), while compound 9 had outstanding binding affinity against Rhizomucor miehei (-8.7 kcal/mol) and against Mycolicibacterium smegmatis (-8.2 kcal/mol). In addition, the binding affinity against white fungus is also outstanding. This time, compounds 8 and 9 had better binding energy, which is -7.8 kcal/mol against Aspergillus luchuensis (1BK1) and -7.6 kcal/mol against Candida auris (6U8J). Finally, the molecular dynamics simulation at 100 ns has proved that they are stable for new medication development. Among the derivatives 1–9, ligands 8 and 9 exhibited potential medicinal characteristics when all of the data were considered.

Synthesis, molecular dynamics, antimicrobial activity and wound healing application of new methylidene dyes based on pyrrolinone esters

A new methylidene dye based on the direct condensation of an aldehyde derivative with a pyrrolinone ester derivative was successfully prepared as well as its quaternary ammonium salt analogue. The structures of all synthesized dyes were confirmed using NMR, Mass and IR spectra. The absorption and emission spectra of the synthesized dyes were investigated. The synthesized methylidene dye and its cationic form showed high molar absorption coefficients and a significant emission of the cationic dye analogue solution was observed. The antibacterial affinity using the disk diffusion method was investigated for six potential skin infection causing microbial pathogens, including two Gram-negative species (Pseudomonas aeruginosa and Proteus mirabilis), two Gram-positive species (Staphylococcus aureus and Staphylococcus epidermidis), and two fungal species (Candida albicans and Rhizomucor miehei) by recording the inhibition zone as well as studying the killing time effect for the prepared dyes. The in vitro wound healing application and the effect of cationized Dye 2 on the healing progress showed very effective and faster healing at a concentration of 100 µg/mL (IC50). Molecular dynamics simulation studies of Dye 1 and Dye 2 were carried out to compute binding free energies using Generalized Born Surface Area (MM/GBSA) in molecular mechanics. Furthermore, computational studies revealed that Dye 2 showed high affinity toward the active site of DNA gyrase B, which provides a solid framework for new structure-based design initiatives.

Influence of enzyme treatment approach on the phenolics content and antioxidant potential of sorghum grain samples

Enzyme-assisted extraction of phenolics was performed from commercial broom, and GK Emese and Farmsugro 180 hybrid sorghum grain residues with cellulolytic and esterolytic cocktails of Rhizomucor miehei NRRL 5282, Gilbertella persicaria SZMC 11086 and Mucor corticolus SZMC 12031 fungi. Results showed an increasing tendency for total phenolic content (TPC) during incubation that was in a positive relation with total flavonoid content (TFC) for most treatments. Best TPC and TFC yields were obtained on broom sorghum with maximal values of 256.9 ± 11.7 mg gallic acid equivalent (GAE)/100 g dry matter (DM) and 159.4 ± 6.8 mg catechin equivalent (CE)/100 g DM, respectively, achieved during R. miehei enzyme treatment. Reducing power and radical scavenging activity assays demonstrated improved antioxidant activity for most treated samples that was in positive correlation (0.942 ≥ r ≥ 0.522) with the TPC and TFC variables. Chromatography analysis revealed hydroxybenzoates, i.e., protocatechuic, 4-hydroxybenzoic and vanillic acids, as major phenolics with yields ranging from 5.40 ± 0.57 to 132.85 ± 14.21 μg/g DM, but the content of hydroxycinnamates increased to a greater extent during the treatments. The enzyme treatments can be reliable methods for enriching phenolic antioxidants in sorghum substances utilizable in gluten-free food products.

Lipase from Rhizomucor miehei onto home-made hydrophobic polymers: Stable and efficient biocatalysts

Immobilized lipases are biotechnological spotlights as tools to improve and enhance enzyme applicability. Here, lipase from Rhizomucor miehei (RML) was immobilized onto core/shell supports, named poly(methyl methacrylate) (PMMA/PMMA); poly(methyl methacrylate) copolymerized with divinylbenzene (PMMA-co-DVB/PMMA-co-DVB); and polystyrene copolymerized with divinylbenzene (PS-co-DVB/PS-co-DVB), and on a commercial non-core/shell porous support (polypropylene - Accurel MP 1000). Different enzyme loadings were evaluated (400 U.g−1, 500 U.g−1, 600 U.g−1, 4000 U.g−1, and 6000 U.g−1), and the immobilized biocatalysts were used in hydrolysis (using p-nitrophenyl laurate (p-NPL) and p-nitrophenyl butyrate (p-NPB) as substrates) and in esterification reactions (using oleic acid and ethanol as substrates). The influence of pH, temperature, and buffer concentration in the hydrolysis of p-NPL was also investigated. The immobilized biocatalysts were compared to free RML and/or to commercially immobilized RML (RM-IM) and/or to Novozym 435. RML interacted differently with each support, being RML-PMMA-co-DVB/PMMA-co-DVB and RML-PMMA/PMMA the biocatalysts with the highest enzymatic activities (hydrolytic activity: >400 U.g−1, using p-NPL; esterification activity: 25,532 U.g−1). Immobilization improved the thermal and pH tolerance and buffer concentration tolerance of RML. Both free RML and the immobilized biocatalysts exhibited their maximum activity at pH 7, with the exception of RML-Accurel MP 1000, which displayed optimal performance at pH 9.0. In addition, RML-PS-co-DVB/PS-co-DVB demonstrated increased activity at 70 °C. Notably, RML-PMMA/PMMA and RML-PMMA-co-DVB/PMMA-co-DVB showcased a maximum activity of 120 U/g, and this was achieved at different temperatures, 30°C and 50°C, respectively. This diverse library of immobilized biocatalysts shows promising potential for application in various industrial processes.

Deciphering the immobilization of lipases on hydrophobic wrinkled silica nanoparticles

In this work, the adsorption of Candida antarctica B (CALB) and Rhizomucor miehei (RML) lipases into hydrophobic wrinkled silica nanoparticles (WSNs) is investigated. WSNs are hydrophobized by chemical vapor deposition. Both proteins are homogeneously distributed inside the pores of the nanoparticles, as confirmed by Transmission Electron Microscopy and Energy Dispersive X-ray measurements. The maximum enzyme load of CALB is twice that obtained for RML. Fourier Transform Infrared Spectroscopy confirms the preservation of the enzyme secondary structure after immobilization for both enzymes. Adsorption isotherms fit to a Langmuir model, resulting in a binding constant (KL) for RML 4.5-fold higher than that for CALB, indicating stronger binding for the former. Kinetic analysis reveals a positive correlation between enzyme load and RML activity unlike CALB where activity decreases along the enzyme load increases. Immobilization allows for enhancing the thermal stability of both lipases. Finally, CALB outperforms RML in the hydrolysis of ethyl-3-hydroxybutyrate. However, immobilized CALB yielded 20 % less 3-HBA than free lipase, while immobilized RML increases 3-fold the 3-HBA yield when compared with the free enzyme. The improved performance of immobilized RML can be explained due to the interfacial hyperactivation undergone by this lipase when immobilized on the superhydrophobic surface of WSNs.

Lipase in-situ immobilized in covalent organic framework: Enzymatic properties and application in the preparation of 1, 3-dioleoyl-2-palmitoylglycerol

In this study, the critical importance of designing an appropriate immobilized carrier and method for free lipase to ensure exceptional biological catalytic activity and stability was emphasized. Covalent organic frameworks (COF-1) were synthesized as a novel porous carrier with an azine structure (-CN-NC-) through the condensation of hydrazine hydrate and benzene-1,3,5-tricarbaldehyde at room temperature. Simultaneously, Rhizomucor miehei lipase (RML) was immobilized within the COF-1 carrier using an in-situ aqueous phase method. Characterization of the carrier and RML@COF-1 and evaluation of the lipase properties of RML and RML@COF-1 through p-Nitrophenyl palmitate hydrolysis were conducted. Additionally, application in the synthesis of 1, 3-dioleoyl-2-palmitoylglycerol (OPO) was explored. The results showed that RML@COF-1 exhibited a high enzymatic loading of 285.4 mg/g. Under 60℃ conditions, the activity of RML@COF-1 was 2.31 times higher than that of free RML, and RML@COF-1 retained 77.25% of its original activity after 10 cycles of repeated use, indicating its excellent thermal stability and repeatability. Under the optimal conditions (10%, 1:8 PPP/OA, 45℃, 5 h), the yield of OPO reached 47.35%, showcasing the promising application prospects of the novel immobilized enzyme synthesized via in-situ aqueous phase synthesis for OPO preparation.

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain LP-N836.

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain LP-N836 by Meito Sangyo Co., Ltd. The native enzyme can be chemically modified to produce a more thermolabile form. The food enzyme is free from viable cells of the production organism. It is intended to be used in the processing of dairy products for the production of cheese and fermented dairy products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.108 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 95 mg TOS/kg bw per day, the mid-dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 880. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches with respiratory allergens and one with a food allergen (mustard) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to mustard proteins, cannot be excluded. Based on the data provided, the Panel concluded that both the native and thermolabile forms of this food enzyme do not give rise to safety concerns under the intended conditions of use.

New Forms of Neuroactive Phospholipids for DHA Enrichment in Brain.

Low levels of docosahexaenoic acid (DHA) in the brain have been related to neurological disorders, like Alzheimer's disease (AD). After ingestion, dietary DHA must cross the blood-brain barrier, where it is absorbed as lysophosphatidylcholine (LPC), due to its role as a preferential DHA carrier in the brain. This work aimed at the production of LPC-DHA extracts to be used in supplementation/food fortification intended neural enrichment in DHA. As it is rich in DHA, especially its phospholipids (PL), Atlantic mackerel (Scomber scombrus, caught in Spring/2022) was used as a raw material. The polar lipids fraction was separated and hydrolysed with Rhizomucor miehei lipase, to enzymatically convert phosphatidylcholine (PC) into LPC. The fish (muscle and by-products) lipids fraction was used for total lipids (TL) content, lipid classes (LC) and fatty acid (FA) profile evaluation, whilst polar lipids extracts were studied for LC production and FA analysis. Muscle TL ranged between 1.45 and 4.64 g/100 g (WW), while by-products accounted for 7.56-8.96 g/100 g, with the highest contents being found in March. However, PL were more abundant in muscle (22.46-32.20% of TL). For polar lipids extracts, PL represented 50.79% of TL, among which PC corresponded to 57.76% and phosphatidylethanolamine to 42.24%. After hydrolysis, nearly half of this PC was converted into LPC. When compared to the initial PC, DHA relative content (33.6% of total FA) was significantly higher after hydrolysis: 55.6% in PC and 73.6% in LPC. Such extract, obtained from this undervalued species, may represent a promising strategy to increase DHA uptake into brain cells while allowing this species to upgrade.

Thermal Stabilization of Lipases Bound to Solid-Phase Triazine-Scaffolded Biomimetic Ligands: A Preliminary Assessment

Biomimetic ligands are synthetic compounds that mimic the structure and binding properties of natural biological ligands. The first uses of textile dyes as pseudo-affinity ligands paved the way for the rational design and de novo synthesis of low-cost, non-toxic and highly stable triazine-scaffolded affinity ligands. A novel method to assess and enhance protein stability, employing triazine-based biomimetic ligands and using cutinase from Fusarium solani pisi as a protein model, has been previously reported. This innovative approach combined the concepts of molecular modeling and solid-phase combinatorial chemistry to design, synthesize and screen biomimetic compounds able to bind cutinase through complementary affinity-like interactions while maintaining its biological functionality. The screening of a 36-member biased combinatorial library enabled the identification of promising lead ligands. The immobilization/adsorption of cutinase onto a particular lead (ligand 3′/11) led to a noteworthy enhancement in thermal stability within the temperature range of 60–80 °C. In the present study, similar triazine-based compounds, sourced from the same combinatorial library and mimicking dipeptides of diverse amino acids, were selected and studied to determine their effectiveness in binding and/or improving the thermal stability of several lipases, enzymes which are closely related in function to cutinases. Three ligands with different compositions were screened for their potential thermostabilizing effect on different lipolytic enzymes at 60 °C. An entirely distinct enzyme, invertase from Saccharomyces cerevisiae, was also assessed for binding to the same ligands and functioned as a ‘control’ for the experiments with lipases. The high binding yield of ligand 3′/11 [4-({4-chloro-6-[(2-methylbutyl)amino]-1,3,5-triazin-2-yl}amino)benzoic acid] to cutinase was confirmed, and the same ligand was tested for its ability to bind lipases from Aspergillus oryzae (AOL), Candida rugosa (CRL), Chromobacterium viscosum (CVL), Rhizomucor miehei (RML) and Rhizopus niveus (RNL). The enzymes CRL, CVL, RNL and invertase showed significant adsorption yields to ligand 3′/11—32, 29, 36 and 94%, respectively, and the thermal stability at 60 °C of free and adsorbed enzymes was studied. CVL and RNL were also stabilized by adsorption to ligand 3′/11. In the case of CRL and invertase, which bound but were not stabilized by ligand (3′/11), other ligands from the original combinatorial library were tested. Between the two alternative ligands, one was effective at stabilizing C. rugosa lipase, while none stabilized invertase.

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain M19-21.

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain M19-21 by Meito Sangyo Co., Ltd. The enzyme is chemically modified to produce a thermolabile form. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in the processing of dairy products for the production of cheese and fermented dairy products. Based on the maximum use levels, dietary exposure was estimated to be up to 0.108 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 226 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure of at least 2093. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches to respiratory allergens and one match to a food allergen (mustard) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to mustard proteins, cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.