Antibacterial Activity of Hen Egg White Lysozyme Denatured by Thermal and Chemical Treatments

The Chicken Egg: An Advanced Material for Tissue Engineering

The chicken egg, an excellent natural source of proteins, has been an overlooked native biomaterial with remarkable physicochemical, structural, and biological properties. Recently, with significant advances in biomedical engineering, particularly in the development of 3D in vitro platforms, chicken egg materials have increasingly been investigated as biomaterials due to their distinct advantages such as their low cost, availability, easy handling, gelling ability, bioactivity, and provision of a developmentally stimulating environment for cells. In addition, the chicken egg and its by-products can improve tissue engraftment and stimulate angiogenesis, making it particularly attractive for wound healing and tissue engineering applications. Evidence suggests that the egg white (EW), egg yolk (EY), and eggshell membrane (ESM) are great biomaterial candidates for tissue engineering, as their protein composition resembles mammalian extracellular matrix proteins, ideal for cellular attachment, cellular differentiation, proliferation, and survivability. Moreover, eggshell (ES) is considered an excellent calcium resource for generating hydroxyapatite (HA), making it a promising biomaterial for bone regeneration. This review will provide researchers with a concise yet comprehensive understanding of the chicken egg structure, composition, and associated bioactive molecules in each component and introduce up-to-date tissue engineering applications of chicken eggs as biomaterials.

Characteristics of hen egg white lysozyme, strategies to break through antibacterial limitation, and its application in food preservation: A review

Hen egg white lysozyme (HEWL) is used as a food additive in China due to its outstanding antibacterial properties. It is listed as GRAS grade (generally recognized as safe) by the United States Food and Drug Administration (FDA, US) and has been extensively researched and used in food preservation. And the industrial production of HEWL already been realized. Given the complex food system that can affect the antibacterial activity of HEWL, and the limitations of HEWL itself on Gram-negative bacteria. Based on the structure and main biological characteristics of HEWL, this paper focuses on reviewing methods to enhance the stability and antibacterial properties of HEWL. Immobilization tactics such as chemically driven self-assembly, embedding and adsorption address the restriction of poor HEWL antibacterial activity effected by external factors. Both intermolecular and intramolecular modification strategies break the bactericidal deficiencies of HEWL itself. It also comprehensively analyzes the current application status and future prospects of HEWL in the food preservation. There was limited research on the biological methods in modifying HEWL. If the HEWL is genetically engineered, it can broaden its antimicrobial spectrum, improve its other biological activities, so as to further expand its application in the food industry. At present, research on HEWL mainly focused on its antibacterial properties, whereas its application in anti-inflammatory and antioxidant effects also presented great potential.

pH-Dependent HEWL-AuNPs Interactions: Optical Study

Optical methods (spectroscopy, spectrofluorometry, dynamic light scattering, and refractometry) were used to study the change in the state of hen egg-white lysozyme (HEWL), protein molecules, and gold nanoparticles (AuNPs) in aqueous colloids with changes in pH, and the interaction of protein molecules with nanoparticles was also studied. It was shown that changing pH may be the easiest way to control the protein corona on gold nanoparticles. In a colloid of nanoparticles, both in the presence and absence of protein, aggregation-deaggregation, and in a protein colloid, monomerization-dimerization-aggregation are the main processes when pH is changed. A specific point at pH 7.5, where a transition of the colloidal system from one state to another is observed, has been found using all the optical methods mentioned. It has been shown that gold nanoparticles can stabilize HEWL protein molecules at alkaline pH while maintaining enzymatic activity, which can be used in practice. The data obtained in this manuscript allow for the state of HEWL colloids and gold nanoparticles to be monitored using one or two simple and accessible optical methods.

Antioxidant Activity of Egg Yolk Protein Hydrolysates Obtained by Enzymatic and Sub-Critical Water Hydrolysis

Obtaining peptides with antioxidant properties by enzymatic hydrolysis has been widely described; however, the use of non-enzymatic methods to obtain peptides with antioxidant capacities has been poorly investigated. In this study, non-soluble proteins obtained from delipidated egg yolk granules were hydrolyzed with trypsin, and with a non-enzymatic method using sub-critical water hydrolysis under a non-oxidizing (nitrogen) and oxidizing (oxygen) atmosphere. The effect of the sub-critical water hydrolysis on the amino acids' composition of the hydrolysates was assessed. Furthermore, the antioxidant capacities of the hydrolysates were evaluated using the ABTS•+ scavenging assay, the DPPH radical scavenging activity assay, and by measuring the reducing power of the peptides, the peptides' ferrous ion chelating capacities, and the antioxidant effect of the peptides on beef homogenates. The hydrolysate obtained by sub-critical water hydrolysis under a nitrogen stream showed similar or better results in the antioxidant tests than those obtained using trypsin hydrolysis, except in the ferrous chelating capacity, where the trypsin hydrolysate showed the best performance. The oxidizing environment promoted by the oxygen in the other sub-critical water hydrolysis method tested produced the peptides with the lowest antioxidant capacities, due to changes in the primary structure of the peptides. These results suggest that the sub-critical water hydrolysis method under a nitrogen stream, in comparison with the enzymatic hydrolysis, is a reliable method to obtain peptides with good antioxidant capacities.

Amphiphilic (di-)gradient copoly(2-oxazoline)s are potent amyloid fibril formation inhibitors

MOTIVATION

Amyloidoses are diseases caused by the accumulation of normally soluble proteins in the form of insoluble amyloids, leading to the gradual dysfunction and failure of various organs and tissues. Inhibiting amyloid formation is therefore an important therapeutic target.

HYPOTHESIS

We hypothesized that mono- and di-gradient amphiphilic copolymers of hydrophilic 2-(m)ethyl-2-oxazoline and hydrophobic 2-aryl-2-oxazolines may inhibit amyloid fibril formation.

EXPERIMENTS

In the model system with hen egg white lysozyme (HEWL) as amyloidogenic protein we determined the effect of these polymers on the amyloid formation by making use of the thioflavin T fluorescence, transmission electron microscopy, isothermal titration calorimetry, and dynamic light scattering.

FINDINGS

We found that some gradient copolymers possess very potent concentration-dependent inhibitory effects on HEWL amyloid formation. Structure-activity relationship revealed that copolymers with higher ratios of aromatic monomeric units had stronger amyloid suppression effects, most plausibly due to the combination of hydrophobic and π-π interactions. The measurements also revealed that the polymers that inhibit amyloid formation most plausibly do so in the form of micelles that interact with the growing amyloid fibril ends, not with isolated HEWL molecules in solution. These findings suggest the potential use of these gradient copolymers as therapeutic agents for amyloidoses.

Effects of Nitro-Oxidative Stress on Biomolecules: Part 1-Non-Reactive Molecular Dynamics Simulations

Plasma medicine, or the biomedical application of cold atmospheric plasma (CAP), is an expanding field within plasma research. CAP has demonstrated remarkable versatility in diverse biological applications, including cancer treatment, wound healing, microorganism inactivation, and skin disease therapy. However, the precise mechanisms underlying the effects of CAP remain incompletely understood. The therapeutic effects of CAP are largely attributed to the generation of reactive oxygen and nitrogen species (RONS), which play a crucial role in the biological responses induced by CAP. Specifically, RONS produced during CAP treatment have the ability to chemically modify cell membranes and membrane proteins, causing nitro-oxidative stress, thereby leading to changes in membrane permeability and disruption of cellular processes. To gain atomic-level insights into these interactions, non-reactive molecular dynamics (MD) simulations have emerged as a valuable tool. These simulations facilitate the examination of larger-scale system dynamics, including protein-protein and protein-membrane interactions. In this comprehensive review, we focus on the applications of non-reactive MD simulations in studying the effects of CAP on cellular components and interactions at the atomic level, providing a detailed overview of the potential of CAP in medicine. We also review the results of other MD studies that are not related to plasma medicine but explore the effects of nitro-oxidative stress on cellular components and are therefore important for a broader understanding of the underlying processes.

Heat-Denatured Lysozyme is a Novel Potential Non-alcoholic Disinfectant Against Respiratory Virus

Respiratory diseases are significant recurrent threats to global public health. Since the 1918 Spanish flu pandemic, seasonal influenza viruses continue to cause epidemics around the world each year. More recently, the COVID-19 global pandemic conducted a public health crisis with more than 6 million deaths and it also severely affected the global economy. Due to the phenomenon that people get infection from objects carrying viruses, it has aroused people's attention to home disinfection. As there is no ideal existing common domestic disinfectant, new and safer antiviral disinfectants are urgently needed. Lysozyme is a natural antibacterial agent widespread in nature and widely used in healthcare and food industry because of is recognized safety. Recently, it has been shown that thermally denatured lysozyme has the ability to kill murine norovirus and hepatitis A virus. In our study, we also demonstrated that heat-denatured lysozyme (HDLz) had an antiviral effect against H1N1 influenza A virus, and we optimized its antiviral activities by testing different heating denaturation conditions, to generalize this property, using pseudotype virus neutralization assay, we found that HDLz can also inhibit the entry of H5N1, H5N6, and H7N1 avian influenza viruses as well as SARS-CoV and SARS-CoV-2 particles in cell with IC50 at the ng/mL range. Finally, using western blot analysis, we provide evidence that HDLz polymerization correlates with antiviral effect, which may be a precious possible quality control test. Altogether, our data support HDLz as a powerful anti-respiratory virus disinfectant as a sole or additive of current disinfectants to reduce concentration of toxic component.

Inhibitory-like Substances Produced by Yeasts Isolated from Andean Blueberries: Prospective Food Antimicrobials

Natural agents from microorganisms have emerged as suitable options to replace chemical preservatives in foods. In this study, the antibacterial activity of cell-free supernatant (CFS) from five native yeasts (Saccharomyces cerevisiae Lev6 and Lev30, C. pseudointermedia Lev8, Candida intermedia Lev9, C. parapsilosis Lev15) and the reference S. boulardi SSB, was evaluated against some indicator food pathogens. The generation of antimicrobials was reliant on strain-, and sugar-supplemented media, which supported yeast growth established at 30 °C and 200 rpm for 48 h. Treatment with proteinase K and catalase was unable to completely abolish the inhibitory effect, indicating that the active components are likely complex combinations of acids, proteins, hydrogen peroxide, and other metabolites. Although there was no impact on Listeria monocytogenes, exposure to CFS and extracellular fractions obtained through precipitation with methanol (PPm) at 120 °C for 60 min significantly (p < 0.05) increased the inhibitory activity against Escherichia coli, Salmonella enterica, Kosakonia cowanii, and Staphylococcus aureus, indicating that the inhibitory activity was stimulated by heat. Likewise, a synergistic inhibitory action against Listeria was obtained following the pretreatment of PPm with EDTA (ethylenediaminetetraacetic acid). These activities were yeast strain-dependent, with Lev6, Lev8, and Lev30 showing the highest activity. In addition, a heat-stable low-molecular-mass molecule under 5 kDa was detected in Lev30. Further research is required to evaluate the mode of action and characterize the composition of the released molecules in the CFS in order to develop a novel biocontrol agent based on yeasts.

Ionovoltaic electricity generation over graphene-nanoplatelets: protein-nanofibril hybrid materials

Continuous harvesting of electricity from the ambient environment has attracted great attention as a facile approach to green and sustainable energy. Natural water evaporation-driven electricity generators with active materials from economical and environment-friendly sources are highly sought after. Herein, we present devices made from a combination of protein nanofibrils (PNFs) and low-cost graphene nanoplatelets (GNPs) that can be employed for electricity generation, simply by partly inserting the device into evaporating standing water. The origin of the electricity generation can be explained by the ionovoltaic effect where ionic motion, driven by evaporating water, leads to movement of charge carriers in the electrically conductive GNP-phase. Moreover, the device performance can be improved by adding a small amount of salt to the active layer. A device, composed of GNP:PNF:AlCl₃, produces a sustained voltage of about 0.48 V, and a current of 89 nA. Furthermore, the device can tolerate saline water, with only a modest decrease of voltage, which provides potential for harvesting electricity from both evaporating saline water and fresh water.

Effects of Dietary Coated Lysozyme on the Growth Performance, Antioxidant Activity, Immunity and Gut Health of Weaned Piglets

The purpose of this study was to evaluate the effects of dietary coated lysozyme on growth performance, serum biochemical indexes, antioxidant activity, digestive enzyme activity, intestinal permeability, and the cecal microbiota in weaned piglets. In total, 144 weaned Large White × Landrace piglets were divided into six treatment groups, with 3 replicates and 8 piglets per replicate: CN, a basal diet; CL-L, CL-M, and CL-H, basal diet supplemented with 100, 150, 500 mg/kg coated lysozyme; UL, basal diet supplemented with 150 mg/kg lysozyme; and Abs, basal diet supplemented with 150 mg/kg guitaromycin for 6 weeks. Compared with the CN and UL diets, dietary CL-H inclusion increased the average daily gain (ADG) and decreased the feed/gain (F/G) ratio of piglets (p < 0.05). The addition of 500 mg/kg coated lysozyme to the diet significantly increased the total protein (TP) and globulin (Glob) plasma levels of weaned piglets (p < 0.05). Supplementation with 500 mg/kg coated lysozyme significantly increased the serum IgM concentration and increased lipase activity in the duodenum (p < 0.05). The addition of coated lysozyme and lysozyme significantly decreased the malondialdehyde (MDA) content, while the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) levels all increased (p < 0.05). High-throughput sequencing results showed that CL-H treatment effectively improved the intestinal microbiome. The relative abundance of Terrisporobacter in the CL-H and CL-M groups was significantly lower than that in the other groups (p < 0.05). LEfSe analysis results showed that the relative abundance of Coprococcus_3 was higher in the CL-M treatment group. The marker species added to the CL-H treatment group was Anaerofilum. In summary, as a potential substitute for feed antibiotics, lysozyme is directly used as a dietary additive, which is inefficient. Therefore, we used palm oil as the main coating material to coat lysozyme. Lysozyme after coating can more effectively improve the growth performance of piglets by improving the intestinal flora, improving the activity of digestive enzymes, reducing the damage to intestinal permeability and oxidative stress in piglets caused by weaning stress, and improving the immunity of piglets.

Cecropin a Improves the Antibacterial Activity of Hen Egg White Lysozyme against Challenging Salmonella enterica Serovars

The prevalence of multidrug-resistant Salmonella enterica among animal- and plant-derived food products threatens global healthcare and economic sectors. Hen egg white lysozyme is widely exploited as a food preservative against Gram-positive pathogens. Nevertheless, its limited penetration of the outer membrane renders it ineffective against Gram-negative bacteria. Herein, we present a safe and effective approach to facilitate HEWL access to peptidoglycan layers using cecropin A. In silico analysis of cecropin A peptide revealed an amphipathic α-helical peptide with potential outer membrane permeabilizing activity through its interaction with both hydrophobic and ionic stabilizing forces. Evaluation of HEWL/cecropin A combination showed a cecropin A dose-dependent bacterial count reduction up to 4.16 and 3.18 ± 0.26 log units against Salmonella enterica ATCC 35664 at the logarithmic and stationary growth phases, respectively. Moreover, the combination displayed antibacterial activity of 2.1 ± 0.31 and ~1 log-unit reductions against Salmonella enterica serovars Kentucky, Typhimurium, and Enteritidis, respectively, whereas Hato and Shangani were found irresponsive. The cytotoxicity assay revealed compatibility of cecropin A with oral epithelial cells. These observations suggest HEWL/cecropin A combination as an effective and safe alternative to lysozyme against Salmonella enterica.

Assessment of safety and quality aspects of boiling treatment of quail eggs

A total of 300 quail eggs were collected randomly from different markets in Cairo and Giza Governorates. Five eggs were represented as one egg sample. Shell and content of each egg were examined for their microbiological contents, sensory evaluation and study of Escherichia coli O157 survival in artificially contaminated eggs. Moreover, qualitative detection of antimicrobial residues by seven plates microbiologically bioassay and confirmed by validated high-performance liquid chromatography (HPLC) methods for positively reacted antimicrobials in raw and boiled samples. There was a significant difference (P &lt; 0·05) between the grading score of eggs after the boiling at 2-, 4-, 5- and 7-min. Based on the survival results, the refrigeration storage and boiling for 5 min of quail eggs was confirmed that such eggs are without E. coli O157. After the boil, the concentrations of oxytetracycline (OTC) and 4-Epi-OTC residues were significantly reduced, and there was no effect on the concentration of sulphadimidine (SDD), amoxicillin (AMO) and Diketo residues. Samples that exceeded the maximum residual limits (MRLs) were 17·0%, 12·0%, 10·0%, 16·0% and 14·0% for SDD, OTC, 4-Epi-OTC, AMO and Diketo, respectively. After boiling, no significant change was noted for SDD, AMO and Diketo, but all OTC and 4-Epi-OTC were completely below MRLs. Therefore, SDD and AMO with their metabolite (Diketo) are heat-stable antimicrobial residues with multiple human health hazards.

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Dietary Fructooligosaccharides Effectively Facilitate the Production of High-Quality Eggs via Improving the Physiological Status of Laying Hens

The focus of this study was to investigate the influence of prebiotics, such as fructooligosaccharides (FOS), on laying performance, egg quality, apparent fecal amino acid digestibility, jejunal morphology, hematological indices, immunological response, and antioxidant capacity in laying hens. A total of 216 healthy Hy-Line Brown laying hens aged 30 weeks were randomly assigned to one of three dietary treatments: basal diet, basal diet supplemented with 0.3 percent FOS, or 0.6 percent FOS. For 84 days, each treatment was fed the corresponding experimental diet. According to the findings, dietary supplementation with FOS enhanced laying performance and egg mass while lowering mortality rate. Albumen height, thick albumen content, Haugh unit, and eggshell thickness were also improved by the prebiotics. Prebiotics also boosted antioxidant status by increasing the activity of antioxidant enzymes, improved morphological development of the jejunum as demonstrated by significant increases in villi height, villi width, ratio of villi height to crypt depth, and reduced crypt depth. The prebiotics group showed a considerable increase in immunoglobulin M, G, and A (IgM, IgG, and IgA) levels, as well as a similar effect on complement proteins (C3). Furthermore, the apparent fecal amino acid digestibility of most essential amino acids was significantly enhanced. Conclusively, fructooligosaccharides at inclusion level of 0.6% efficiently enhanced laying performance and production of high-quality eggs while positively modulating amino acid digestibility, jejunal morphology, antioxidant status, and immune functions of the laying hens.

Dual functional carbonate-hydroxyapatite nanocomposite from Pinctada maxima and egg-white for bone tissue engineering

This study aims to design a 3D carbonate-hydroxyapatite (CHA)/sago (S) based egg white (EW) microstructure with antibacterial properties to improve the performance of bone grafts for bone tissue engineering. In this study, Pinctada maxima (P. maxima) shell was used as a calcium (Ca) source in CHA synthesis. The annealing temperature of CHA at 900, 1000, and 1100 °C affected microstructural and lattice parameters, with stoichiometry 1.72-1.77, and B-type CHA was identified. CHA/S with various concentrations of EW (10 and 30 wt.%) effectively increased pore size and porosity. XRD spectra confirmed that sago and EW in CHA nanocomposite stable the crystal structure. FTIR spectrum shows protein phosphorylation in CHA nanocomposite due to PO₄^3- ion exchange. In-vitro bioactivity of CHA-S10 (MTT assay) showed increased cell viability and optical density (OD; 24-48 h) to control. Antibacterial activity of CHA-S10 and CHA/S (control) against bacteria associated with periodontal disease and bone infection (Actinobacillus actinomycetemcomitans [A. actinomycetemcomitans], Porphyromonas gingivalis [P. gingivalis], Fusobacterium nucleatum [F. nucleatum; gram negative], and Staphylococcus aureus [S. aureus; gram positive]) by disc diffusion method showed that CHA-S10 and CHA/S had strong antibacterial activity. In conclusion, EW's properties had proven the CHA/S/EW as bone grafts, effectively increasing pore size, porosity, biocompatibility, and strong antibacterial properties.

Inhibition of lysozyme lytic activity by Ivy derived from Photobacterium damselae subsp. piscicida

A pseudotuberculosis pathogen, Photobacterium damselae subsp. piscicida (Pdp), has caused enormous economic damage to yellowtail aquaculture in Japan. The Ivy gene has been discovered in plasmid of Pdp, and it has been proposed that it may help bacteria evade lysozyme-mediated lysis during interaction with an animal host. However, the lysozyme-inhibiting activity of Pdp-derived Ivy (Ivy-Pdp) is unknown, and it is unclear whether it acts as a virulence factor for host biophylaxis. In this study, the inhibitory effect of Ivy-Pdp on lysozyme was evaluated by expressing and purifying the recombinant Ivy-Pdp protein (rIvy-Pdp). The rIvy-Pdp protein inhibited hen egg white lysozyme activity in an rIvy-Pdp-concentration-dependent manner, and its inhibitory effect was similar under different temperature and pH conditions. The serum and skin mucus of the yellowtail (which is the host species of Pdp), Japanese flounder, and Nile tilapia showed bacteriolytic activity. In contrast, the addition of rIvy-Pdp inhibited the lytic activity in the serum of these fish species. In particular, it significantly inhibited lytic activity in the serum and skin mucus of Nile tilapia. On the basis of these results, we suggest that Ivy-Pdp is a temperature- and pH-stable lysozyme inhibitor. Additionally, Ivy-Pdp inhibited the lytic activity of lysozyme, which is involved in host biophylaxis. In summary, we inferred that Ivy-Pdp is an important factor that diminishes the sterilization ability of C-type lysozyme when Pdp infects the host.

An Overview of Antimicrobial Activity of Lysozyme and Its Functionality in Cheese

Due to the concern of consumers about the presence of synthetic preservatives, researchers and food manufacturers have recently conducted extensive research on the limited use of these preservatives and the introduction and use of natural preservatives, such as herbal extracts and essential oils, bacteriocins, and antimicrobial enzymes. Lysozyme is a natural enzyme with antimicrobial activity that has attracted considerable attention to be potentially utilized in various industries. Since lysozyme is an intrinsic component of the human immune system and has low toxicity; it could be considered as a natural antimicrobial agent for use in food and pharmaceutical industries. Lysozyme exerts antimicrobial activity against microorganisms, especially Gram-positive bacteria, by hydrolyzing 1,4-beta-linkages between N-acetylmuramic acid and N-acetylglucosamine in the cell wall. In addition, increased antimicrobial activity of lysozyme against Gram-negative bacteria could be achieved by the modification of lysozyme through physical or chemical interactions. Lysozyme is presented as a natural preservative in mammalian milk and can be utilized as a bio-preservative in dairy products, such as cheese. Both bacteria and fungi can contaminate and spoil the cheese; especially the one that is made traditionally by raw milk. Furthermore, uncontrolled and improper processes and post-pasteurization contamination can participate in the cheese contamination. Therefore, besides common preservative strategies applied in cheese production, lysozyme could be utilized alone or in combination with other preservative strategies to improve the safety of cheese. Hence, this study aimed to review the antimicrobial properties of lysozyme as natural antimicrobial enzyme and its functionality in cheese.

Design, synthesis and characterization of lysozyme-gentisic acid dual-functional conjugates with antibacterial/antioxidant activities

Both microbiological and chemical food spoilages remain to be the major challenges in the food industry's efforts to combat food waste and loss because of the lack of high efficacy food preservatives. In this study, dual-functional conjugates that simultaneously suppress both lipid oxidation and microorganism growth are fabricated by covalently conjugating natural antioxidant gentisic acid (GA) on native antibacterial lysozyme (Lys). The mixing ratio of Lys and GA determines the particle size, morphology, antioxidant activity, and antimicrobial performance of the ensuing conjugates. With more of GA being grafted, a drastic decrease in the net surface charge with the concomitant occurrence of aggregations are observed in the conjugates. The maximum antioxidant activity and antibacterial performance of the conjugates is achieved when Lys:GA molar ratio is 1:112. The findings could guide the rational design of future functional food ingredients that combine multiple natural bioactive compounds to effectively intervene food waste and loss.

Tailored enzymes as next-generation food-packaging tools

Enzymes have the potential for biotransformation in the food industry. Engineering tools can be used to develop tailored enzymes for food-packaging systems that perform well and retain their activity under adverse conditions. Consequently, novel tailored enzymes have been produced to improve or include new and useful characteristics for intelligent food-packaging systems. This review discusses the protein-engineering tools applied to create new functionality in food-packaging enzymes. The challenges in applications and anticipated directions for future developments are also highlighted. The development and discovery of tailored enzymes for smart food packaging is a promising way to ensure safe and high-quality food products.

In vitro bioactivity of 3D microstructure hydroxyapatite/collagen based-egg white as an antibacterial agent

The present study aims to design 3D scaffold hydroxyapatite (HA)/collagen (Coll) based egg-white (EW) as antibacterial properties. The calcium source in HA synthesis derived from the Pinctada maxima shell cultivated on Bali Island has proven biocompatibility, and the compressive strength exceeded human bone. HA synthesis by precipitation with heat treatment in oven-dried at 80°C (HA-80) and annealed at 900°C (HA-900), has crystallinity 48% and 85%, respectively, were used for scaffold design. The physicochemical properties of X-ray diffractometer spectra showed that increasing temperature affected the crystallinity and HA phase formed. Furthermore, the crystal structure of HA changed in nanocomposite due to the substitution of Coll and EW, and the Fourier transform infrared spectroscopy spectra confirmed that the absorption peak of the phosphate group (1027-1029 cm^-1 ) decreased intensity, presumably by protein binding of EW and Coll. The cell viability of HA/Coll/EW in 24, 48, and 72 h incubation period was 112.34 ± 4.36, 104.89 ± 3.41, 72.88 ± 6.85, respectively. The decreases of cell viability due to high cell density and reduced nutrients in wells. Antibacterial activity of HA/Col/EW exhibited a strong zone of inhibition against bacteria causing periodontitis; Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Staphylococcus aureus.

Antimicrobial coatings based on chitosan to prevent implant-associated infections: A systematic review

Despite the advancements in material science and surgical techniques, the incidence of implant-associated infections (IAIs) has increased significantly. IAIs are mainly caused by microbial adhesion and biofilm formation on implant surfaces. In this study, we aimed to evaluate and critically discuss the antimicrobial efficacy of chitosan-based coatings to prevent the occurrence of IAIs. For this purpose, a PRISMA-oriented systematic review was conducted based on predefined criteria and forty studies were selected for qualitative analysis. Results indicated that chitosan (CS) association with enzymes and antimicrobial peptides improves its antimicrobial activity and extends its use in a broad range of physiological conditions. Likewise, CS association with polymers resulted in enhanced antimicrobial and anti-adhesive coatings with desirable properties, such as biocompatibility and durability, for implantable medical devices (IMDs). These findings can assist researchers in the design of new CS coatings for application in IMDs.

Applications of Lysozyme, an Innate Immune Defense Factor, as an Alternative Antibiotic

Lysozyme is a ~14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi. Three main different types of lysozymes are known: the c-type (chicken or conventional type), the g-type (goose type), and the i-type (invertebrate type). It has long been the subject of several applications due to its antimicrobial properties. The problem of antibiotic resistance has stimulated the search for new molecules or new applications of known compounds. The use of lysozyme as an alternative antibiotic is the subject of this review, which covers the results published over the past two decades. This review is focused on the applications of lysozyme in medicine, (the treatment of infectious diseases, wound healing, and anti-biofilm), veterinary, feed, food preservation, and crop protection. It is available from a wide range of sources, in addition to the well-known chicken egg white, and its synergism with other compounds, endowed with antimicrobial activity, are also summarized. An overview of the modified lysozyme applications is provided in the form of tables.

Development of Silica Nanoparticle Supported Imprinted Polymers for Selective Lysozyme Recognition

Protein imprinted MIPs show notable potential for applications in many analytical areas such as clinical analysis, medical diagnostics and environmental monitoring, but also in drug delivery scenarios. In this study, we present various modifications of two different synthesis routes to create imprinted core-shell particles serving as a synthetic recognition material for the protein hen egg white (HEW) lysozyme. HEW lysozyme is used as food additive E 1105 for preservation due to its antibacterial effects. For facilitating quality and regulatory control analysis in food matrices, it is necessary to apply suitable isolation methods as potentially provided by molecularly imprinted materials. The highest binding capacity achieved herein was 58.82 mg/g with imprinting factors ranging up to 2.74, rendering these materials exceptionally suitable for selectively isolating HEW lysozyme.

Complexation of CXCL12, FGF-2 and VEGF with Heparin Modulates the Protein Release from Alginate Microbeads

Long-term delivery of growth factors and immunomodulatory agents is highly required to support the integrity of tissue in engineering constructs, e.g., formation of vasculature, and to minimize immune response in a recipient. However, for proteins with a net positive charge at the physiological pH, controlled delivery from negatively charged alginate (Alg) platforms is challenging due to electrostatic interactions that can hamper the protein release. In order to regulate such interactions between proteins and the Alg matrix, we propose to complex proteins of interest in this study - CXCL12, FGF-2, VEGF - with polyanionic heparin prior to their encapsulation into Alg microbeads of high content of α-L-guluronic acid units (high-G). This strategy effectively reduced protein interactions with Alg (as shown by model ITC and SPR experiments) and, depending on the protein type, afforded control over the protein release for at least one month. The released proteins retained their in vitro bioactivity: CXCL12 stimulated the migration of Jurkat cells, and FGF-2 and VEGF induced proliferation and maturation of HUVECs. The presence of heparin also intensified protein biological efficiency. The proposed approach for encapsulation of proteins with a positive net charge into high-G Alg hydrogels is promising for controlled long-term protein delivery under in vivo conditions.

Comparison of the Antimicrobial and Hemolytic Activities of Various Forms of Silver (Ions, Nanoparticles, Bioconjugates) Stabilized in a Zeolite Matrix

A quantitative and qualitative comparison of the antimicrobial and hemolytic activities of silver in various states, in the form of ions, nanoparticles, and bioconjugates with the antimicrobial protein lysozyme stabilized in an inert zeolite matrix, has been carried out. A synthetic zeolite with a β structure was chosen as a zeolite matrix. Using the ion-exchange method, the method of chemical reduction, and treating the matrix with a silver hydrosol with specified characteristics, samples of zeolites with the same silver content in various forms (Ag⁺, Ag° - Ag°/Lyz) in the amounts of 0.8 and 5 wt % have been synthesized. The samples obtained were studied by a complex of physicochemical research methods: X-ray diffraction, UV absorption spectroscopy, low-temperature nitrogen adsorption, electron microscopy, and atomic absorption. Antimicrobial activity was assessed against antibiotic-resistant Gram-negative microbe (e.g., Escherichia coli ML-35, Pseudomonas aeruginosa 522/17 MDR, Klebsiella pneumoniae ESBL 344) and Gram-positive microbe (e.g., Staphylococcus aureus 1399/17). The hemolytic activity in relation to human erythrocytes was estimated. The results obtained showed significant antimicrobial activity with a simultaneously high hemolytic activity of ionic silver. Silver nanoparticles have a lower level of antimicrobial activity and toxicity. Bioconjugates of silver nanoparticles and lysozyme showed an optimal combination of antimicrobial properties and lack of hemolytic activity.

How Do Proteins Associate with Nanoscale Metal-Organic Framework Surfaces?

It is well known that colloidal nanomaterials, upon exposure to a complex biological medium, acquire biomolecules on their surface to form coronas. Porous nanomaterials present an opportunity to sequester biomolecules and/or control their orientation at the surface. In this report, a metal-organic framework (MOF) shell around gold nanorods was compared to MOF nanocrystals as potential protein sponges to adsorb several common proteins (lysozyme, beta-lactoglobulin-A, and bovine serum albumin) and potentially control their orientation at the surface. Even after correction for surface area, MOF shell/gold nanorod materials adsorbed more protein than the analogous nanoMOFs. For the set of proteins and nanomaterials in this study, all protein-surface interactions were exothermic, as judged by isothermal titration calorimetry. Protein display at the surfaces was determined from limited proteolysis experiments, and it was found that protein orientation was dependent both on the nature of the nanoparticle surface and on the nature of the protein, with lysozyme and beta-lactoglobulin-A showing distinct molecular positioning.

Microwave Modification as an Excellent Way to Produce Unique Lysozyme with Potential for Food and Human Health

Thermal modification is an effective method of converting lysozyme into a protein with a very strong bactericidal effect and a broad multidirectional application potential. In this research, we used our innovative method, which involves the use of microwave radiation, in the lysozyme modification process. With the optimization of modification conditions as the main purpose of the study, we focused on the assessment of the impact of a strongly acidic modification environment and the duration of modification on the effectiveness of the modification of lysozyme. Moreover, an innovation was introduced and included the use of a commercially produced liquid lysozyme concentrate (LLC) as the starting material instead of the dried form that is commonly used. The obtained results showed that the modified preparations contained an abundant amount of oligomers, and the surface hydrophobicity increased by more than 50% compared to the native form of the enzyme, which means that the modification had a strong influence on the effectiveness of the antibacterial activity. Moreover, these changes made it possible to obtain preparations with complete solubility, which could not be obtained with other thermal methods. Thus, using microwave radiation to modify LLC is a unique and effective modification scheme because it can obtain the highest quality of a large number of attractive products in a simple and fast way with multidirectional application potential, especially in food technology, medicine, pharmacology, and veterinary medicine.

Plasma treatment causes structural modifications in lysozyme, and increases cytotoxicity towards cancer cells

Bacterial and mammalian proteins, such as lysozyme, are gaining increasing interest as anticancer drugs. This study aims to modify the lysozyme structure using cold atmospheric plasma to boost its cancer cell killing effect. We investigated the structure at acidic and neutral pH using various experimental techniques (circular dichroism, fluorescence, and mass spectrometry) and molecular dynamics simulations. The controlled structural modification of lysozyme at neutral pH enhances its activity, while the activity was lost at acidic pH at the same treatment conditions. Indeed, a larger number of amino acids were oxidized at acidic pH after plasma treatment, which results in a greater distortion of the lysozyme structure, whereas only limited structural changes were observed in lysozyme after plasma treatment at neutral pH. We found that the plasma-treated lysozyme significantly induced apoptosis to the cancer cells. Our results reveal that plasma-treated lysozyme could have potential as a new cancer cell killing drug.

Unconventional effects of long-term storage of microwave-modified chicken egg white lysozyme preparations

Thermal modification is an effective method that induces significant expansion of the antimicrobial properties and other valuable properties of chicken egg white lysozyme. In our latest research, a new innovative method of enzyme modification was developed, in which microwave radiation was used as an energy source to process liquid lysozyme concentrate (LLC). After modification, high-quality preparations were obtained. However, long-term storage in a concentrated form initiated various processes that caused darkening over time and could also lead to other significant changes to their structure and, consequently, to their functional properties. This necessitated multidirectional research to explain this phenomenon. This paper presents the results of research aimed at assessing the physicochemical changes in the properties of microwave-modified lysozyme in the form of a liquid concentrate after long-term storage under refrigeration conditions. The assessment also considered the conditions under the acidity of the modifying medium and the duration of the microwave modification. The analysis showed that the values of the basic parameters determining the quality and usefulness of the modified enzyme significantly improved during long-term storage of the preparations. The greatest changes were observed in the preparations modified for the longest time and in the most acidic environment (process time 260 s, pH 2.0), the number of oligomers under these conditions increased by 18% after 12 months of holding, and the surface hydrophobicity increased by as much as 31%. In addition, microbiological tests showed that the preparations of microwave-modified lysozyme had an effect on gram-positive bacteria as well as on gram-negative, and this effect was significantly enhanced after 12 months. The results confirm that LLC modification with microwave radiation is a highly efficient method to prepare high-quality and high utility potential lysozyme. Notably, an interesting and important phenomenon was the observation of the unconventional behaviour of the preparations during their long-term storage, which increased their utility potential significantly.

Drug-Free Enzyme-Based Bactericidal Nanomotors against Pathogenic Bacteria

The low efficacy of current conventional treatments for bacterial infections increases mortality rates worldwide. To alleviate this global health problem, we propose drug-free enzyme-based nanomotors for the treatment of bacterial urinary-tract infections. We develop nanomotors consisting of mesoporous silica nanoparticles (MSNPs) that were functionalized with either urease (U-MSNPs), lysozyme (L-MSNPs), or urease and lysozyme (M-MSNPs), and use them against nonpathogenic planktonic Escherichia coli. U-MSNPs exhibited the highest bactericidal activity due to biocatalysis of urea into NaHCO₃ and NH₃, which also propels U-MSNPs. In addition, U-MSNPs in concentrations above 200 μg/mL were capable of successfully reducing 60% of the biofilm biomass of a uropathogenic E. coli strain. This study thus provides a proof-of-concept, demonstrating that enzyme-based nanomotors are capable of fighting infectious diseases. This approach could potentially be extended to other kinds of diseases by selecting appropriate biomolecules.

Unfolding and Aggregation of Lysozyme under the Combined Action of Dithiothreitol and Guanidine Hydrochloride: Optical Studies

Using a number of optical techniques (interferometry, dynamic light scattering, and spectroscopy), denaturation of hen egg white lysozyme (HEWL) by treatment with a combination of dithiothreitol (DTT) and guanidine hydrochloride (GdnHCl) has been investigated. The denaturing solutions were selected so that protein denaturation occurred with aggregation (Tris-HCl pH = 8.0, 50 mM, DTT 30 mM) or without aggregation (Tris-HCl pH = 8.0, 50 mM, DTT 30 mM, GdnHCl 6 M) and can be evaluated after 60 min of treatment. It has been found that denatured by solution with 6 M GdnHCl lysozyme completely loses its enzymatic activity after 30 min and the size of the protein molecule increases by 1.5 times, from 3.8 nm to 5.7 nm. Denaturation without of GdnHCl led to aggregation with preserving about 50% of its enzymatic activity. Denaturation of HEWL was examined using interferometry. Previously, it has been shown that protein denaturation that occurs without subsequent aggregation leads to an increase in the refractive index (Δn ~ 4.5 × 10-5). This is most likely due to variations in the HEWL-solvent interface area. By applying modern optical techniques conjointly, it has been possible to obtain information on the nature of time-dependent changes that occur inside a protein and its hydration shell as it undergoes denaturation.

Chemically modified glycogens: how they influence formation of amyloid fibrils?

The formation of amyloid fibrils from certain proteins stays behind a number of pathologies, so-called amyloidoses. Glycosaminoglycans are polysaccharides and are known natural constituents of amyloids in vivo. However, little is known about the effect of other naturally abundant polysaccharides, and even less is known about the effect of chemically modified polysaccharides on the formation of amyloid fibrils. In the case of low-molecular weight compounds, aromatic substances are known to often influence amyloid formation significantly. We investigated the influence of glycogen (GG) and several modifications of GG with cinnamoyl groups, benzoyl groups and phenylacetyl groups. As model systems, hen egg-white lysozyme (HEWL) and amyloid beta peptide (1-42) (Aβ1-42), which is an Alzheimer disease-relevant system, were used. The fluorescence of thioflavin-T (ThT) was used for the rapid detection of fibrils, and the fluorescence results were confirmed by transmission electron microscopy (TEM). Other techniques, such as isothermal titration calorimetry (ITC) and dynamic light scattering (DLS), were employed to determine the interactions between HEWL and the modifications. We achieved similar results with both model systems (HEWL and Aβ1-42). We showed that π-π interactions played an important role in the process of amyloid fibril formation because fundamental changes were observed in this process even with a very small number of groups containing an aromatic ring. It was found that almost all GG modifications accelerated the formation of amyloid fibrils in both model systems, HEWL and Aβ1-42, except for GG-Ph1 (1.6 mol% phenylacetyl groups), which had a retarding effect compared to all other modifications.

New possibilities for egg white lysozyme: heat-denatured lysozyme partially inactivates select foot-and-mouth disease virus strains

Foot-and-mouth disease (FMD) is one of the most contagious diseases of cloven-hoofed animals. Disinfectants are used to inactivate FMD virus (FMDV) in Japan. Reports that heat-denatured lysozyme inactivates bacteria as well as viruses, such as norovirus and hepatitis A virus, led us to determine its effects on FMDV. We show here that heat-denatured lysozyme partially inhibited the infectivity of FMDV O/JPN/2010-1/14C but of FMDVs A/TAI/46-1/2015 and Asia1/Shamir (ISR/3/89). Further, heat-denatured lysozyme variably reduced RNA loads of FMDVs O/JPN/2010-1/14C, O/MOG/2/Ca/BU/2017, O/Taiwan/1997, Asia1/Shamir (ISR/3/89), Asia1/TUR/49/2011, SAT1/KEN/117/2009, SAT2/SAU/6/2000 and SAT3/ZIM/3/83 but could not those of O/JPN/2000, A/TAI/46-1/2015, A₂₂/IRQ/24/64, A₁₅/TAI/1/60 and C/PHI/7/84. These findings indicate that heat-denatured lysozyme may serve as a new disinfectant against FMDV.

Chemically Denatured Structures of Porcine Pepsin using Small-Angle X-ray Scattering

Porcine pepsin is a gastric aspartic proteinase that reportedly plays a pivotal role in the digestive process of many vertebrates. We have investigated the three-dimensional (3D) structure and conformational transition of porcine pepsin in solution over a wide range of denaturant urea concentrations (0–10 M) using Raman spectroscopy and small-angle X-ray scattering. Furthermore, 3D GASBOR ab initio structural models, which provide an adequate conformational description of pepsin under varying denatured conditions, were successfully constructed. It was shown that pepsin molecules retain native conformation at 0–5 M urea, undergo partial denaturation at 6 M urea, and display a strongly unfolded conformation at 7–10 M urea. According to the resulting GASBOR solution models, we identified an intermediate pepsin conformation that was dominant during the early stage of denaturation. We believe that the structural evidence presented here provides useful insights into the relationship between enzymatic activity and conformation of porcine pepsin at different states of denaturation.

Production of White, Red and Black Quinoa (Chenopodium quinoa Willd Var. Real) Protein Isolates and Its Hydrolysates in Germinated and Non-Germinated Quinoa Samples and Antioxidant Activity Evaluation

Red, black and white seeds quinoa were germinated at 28 °C during 24 (G1), 48 and 72 h (G3). Red quinoa presented a higher percentage of germination with a value of 46% of germination at 72 h. Quinoa protein isolate (QPI) was obtained by alkaline extraction (pH 8.0) followed by an isoelectric precipitation (pH 4.5) from white, red and black quinoa seeds, germinated QPI-G1 or QPI-G3 and non-germinated QPI-NG, Chenopodium quinoa Willd var. Real. QPI-G1, QPI-G3 and QPI-NG were subject to a simulated gastric digestion (DG) and in vitro duodenal digestion (DD). The antioxidant activity was evaluated using the 1, 1-diphenyl-2-picryl hydrazyl (DPPH), azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC) methods. Gastric and duodenal digest of QPI-NG and QPI-G1 and QPI-G3 from white, red and black quinoa presented antioxidant activity. QPI-G1-DD of white quinoa presented the highest antioxidant activity with a DPPH value of 167.98 µmoL TE/g of digest, QPI-G1-DD of red quinoa with an ABTS value of 204.86 µmoL TE/g of digest and QPI-G1-DD of black quinoa with an ORAC value of 401.42 µmoL TE/g of digest. QPI-G3-DD of white quinoa presented higher antioxidant activity with a DPPH value of 186.28 µmoL TE/g of sample, QPI-G3-DD of red quinoa with an ABTS value of 144.06 µmoL TE/g of digest and QPI-G3-DD of black quinoa with an ORAC value of 395.14 µmoL TE/g of digest. The inhibition of reactive oxygen species (ROS) production in the zebrafish embryo model (Danio rerio) was evaluated. Protein profiles of QPI from white, red and black from germinated quinoa and non-germinated quinoa were similar with proteins between 10 kDa to 100 kDa with the presence of globulins 11S and 7S and 2S albumins.

The Golden Egg: Nutritional Value, Bioactivities, and Emerging Benefits for Human Health

Egg is an encapsulated source of macro and micronutrients that meet all requirements to support embryonic development until hatching. The perfect balance and diversity in its nutrients along with its high digestibility and its affordable price has put the egg in the spotlight as a basic food for humans. However, egg still has to face many years of nutritionist recommendations aiming at restricting egg consumption to limit cardiovascular diseases incidence. Most experimental, clinical, and epidemiologic studies concluded that there was no evidence of a correlation between dietary cholesterol brought by eggs and an increase in plasma total-cholesterol. Egg remains a food product of high nutritional quality for adults including elderly people and children and is extensively consumed worldwide. In parallel, there is compelling evidence that egg also contains many and still-unexplored bioactive compounds, which may be of high interest in preventing/curing diseases. This review will give an overview of (1) the main nutritional characteristics of chicken egg, (2) emerging data related to egg bioactive compounds, and (3) some factors affecting egg composition including a comparison of nutritional value between eggs from various domestic species.