Lysozyme, scientifically known as N-acetylmuramidase, is a naturally occurring enzyme found abundantly in various fluids and tissues—ranging from egg whites and milk to tear fluid and saliva. Discovered over a century ago by Alexander Fleming, lysozyme has since become famous not merely for its antimicrobial activity, but also for its widespread integration into daily products such as foods, beverages, packaging, and even household items.

This comprehensive exploration will detail lysozyme's presence in everyday life, focusing on its multifaceted roles within food systems, consumer products, and public health applications.

Natural Occurrence of Lysozyme

Lysozyme is a highly conserved antimicrobial enzyme that plays a pivotal role in the innate immune system across a wide range of species, from invertebrates to mammals. Its widespread presence and consistent functionality underscore its evolutionary importance as a first line of defense against microbial invasion.

• Egg Whites: One of the richest and most well-characterized natural sources of lysozyme is egg white, particularly from chicken eggs, where it comprises approximately 3–4% of the total protein content. This high concentration contributes to the protective properties of the egg, safeguarding the developing embryo against bacterial contamination.
• Human Secretions: In humans, lysozyme is found abundantly in several exocrine secretions. These include tears, saliva, nasal mucus, and breast milk, where it contributes to mucosal immunity by continuously surveilling and degrading potential pathogens that come into contact with epithelial surfaces. In breast milk, lysozyme plays a particularly vital role in protecting infants, whose immune systems are still developing, by limiting microbial colonization of the gut and promoting a healthy microbiota.
• Immune Cells: Beyond secretions, lysozyme is also actively produced and secreted by immune cells, notably neutrophils and macrophages, during inflammatory responses. Upon infection or tissue injury, these cells release lysozyme into the extracellular space, where it acts synergistically with other antimicrobial peptides and enzymes to neutralize invading bacteria. In phagocytes, lysozyme is stored in azurophilic granules, from which it is released into phagolysosomes to digest engulfed pathogens.

This broad and strategic distribution of lysozyme across biological fluids and immune cell types reflects its critical function in host defense. Its conservation across species—from birds to mammals—emphasizes its evolutionary significance as a natural antimicrobial agent, finely tuned to operate at both the molecular and cellular levels of immune protection.

Role in Food and Beverage Applications

• Cheese and Dairy Products: Lysozyme serves extensively as a natural preservative in cheeses—especially hard and semi-hard varieties like Gouda and Parmigiano. Its primary role is to prevent "late-blowing," a defect caused by Clostridium tyrobutyricum, preserving both flavor and texture. The Codex General Standard and EU regulations (E 1105) permit its use under Good Manufacturing Practice.
• Wine and Beer Production: In winemaking, lysozyme (up to 500 ppm per EU resolution OENO 10/97) inhibits lactic acid bacteria responsible for spoilage and uncontrolled malolactic fermentation. It also helps clarify wines and maintain foam stability. In unpasteurized beers, doses around 300 mg/L counteract spoilage by Pediococcus and Lactobacillus species.
• Ready-to-Eat Meat and Seafood: Lysozyme-treated packaging or direct application extends shelf life of deli meats, sausages, poultry, and seafood by dramatically reducing Listeria monocytogenes and other Gram-positive contaminants. Studies report reductions of over 99% in slices of turkey and bacon stored under refrigerated conditions.
• Fresh Produce and Beverages: Lysozyme coatings or washing solutions help minimize spoilage in fruits and vegetables while preserving sensory qualities. When combined with other antimicrobials such as nisin, it effectively delays bacterial growth in juices and fermented beverages without altering flavor.

Figure 1. Lysozyme can be used for food preservation. (Bergamo and Sava, 2024)

Lysozyme in Food Packaging and Preservation Systems

• Antimicrobial Packaging Films: Lysozyme is incorporated into edible films and coatings made from biodegradable materials such as chitosan, alginate, or whey protein. These coatings slowly release lysozyme to inhibit both Gram-positive and Gram-negative bacteria on food surfaces. Composite films combining lysozyme with dextran, sodium alginate, or nanocellulose display enhanced activity against pathogens such as S. aureus, E. coli, and Pseudomonas fluorescens.
• Nanotechnology-Enhanced Preservation: Lysozyme immobilized in chitosan nanoparticles or conjugated via Maillard reaction with polysaccharides shows significantly enhanced stability and activity—some formulations boosted enzyme activity by over 250%, extending the shelf life of delicate foods like strawberries by several days.
• Smart Sensors Embedded in Packaging: Innovative sensors using lysozyme-stabilized gold fluorescent clusters (GFCs) can detect trace amounts of harmful metal ions (e.g., Hg²⁺) through fluorescence quenching, offering rapid, non-toxic ways to monitor food contamination.

Nutrition and Dietary Exposure

• Consumption via Food Products: Consumers encounter lysozyme mainly through cheese, wine, unpasteurized beverages, and some meat products. While typically present in minimal and regulated quantities, it may convey both antimicrobial benefits and allergen exposure—particularly for individuals with egg allergies.
• Labeling and Allergenicity: Due to its egg origin, lysozyme is a recognized allergen under EU and global labeling regulations. Even minimal residual lysozyme can affect highly sensitive individuals. Non-egg-derived lysozyme products (e.g., plant-based or microbial expression systems) are emerging as alternatives.

Agricultural and Animal Feed Uses

• Livestock and Poultry Feeds: Lysozyme has been adopted as an antibiotic substitute in swine diets, where it improves growth performance, feed efficiency, and gut health through microbial modulation—without contributing to antibiotic resistance. Its effects include enhanced intestinal morphology, immunoglobulin secretion, and altered microbiota composition.
• Aquaculture: Adding lysozyme to feed enhances the disease resistance of aquaculture species, such as shrimp and tilapia, by suppressing pathogens like Vibrio spp. It also improves overall health and growth metrics.

Household, Bio-engineering, and Diagnostic Applications

• Biosensors and Diagnostics: Lysozyme-based biosensors, including colorimetric platforms with gold nanoparticles or graphene oxides, allow rapid detection of spoilage or pathogenic bacteria in food and clinical samples. Their sensitivity, safety, and portability make them ideal for point-of-care and industrial environments.
• Laboratory and Biomedical Uses: In research laboratories, lysozyme is widely used to lyse Gram-positive bacterial cells for DNA/RNA extraction and recombinant protein production. Beyond basic use, lysozyme crystals serve as nanoreactors in materials science and catalysis studies.

Safety, Allergenicity, and Regulation

Lysozyme enjoys GRAS (Generally Recognized as Safe) status in many jurisdictions, particularly for use in foods, beverages, and biomedical formulations. However:

• Allergy risk remains for egg-allergic individuals, prompting careful labeling.
• Regulatory bodies (e.g., FDA, EFSA) enforce concentration limits (e.g. ≤500 ppm in wines) and allergen declarations.

Alternative non-egg-derived lysozyme options are being developed to accommodate sensitive populations.

Recommended Products

In summary, lysozyme is more than just a biological enzyme—it is a molecular ambassador between nature and applied technology. Despite its extensive use, challenges remain—most notably allergenicity and the limited spectrum against Gram-negative bacteria. Innovations in formulation, alternative sourcing, and material science continue to expand lysozyme's utility in everyday life. As consumers increasingly demand clean-label products, sustainable ingredients, and natural preservatives, lysozyme occupies a unique position. Its molecular power, safety profile, and multi-domain applications make it a cornerstone of modern food science, agriculture, and biotech innovation.

At Creative Enzymes, we offer high-quality lysozyme products for safety, performance, and versatility across food, agriculture, and biotechnology. Explore our lysozyme solutions to support your clean-label, science-driven innovations. Contact us today for more information.