An enzyme occurring naturally in egg white, human tears, saliva, and other body fluids, capable of destroying the cell walls of certain bacteria and thereby acting as a mild antiseptic. Lysozyme protects us from the ever present danger of bacterial infection. It is a small enzyme that attacks the protective cell walls of bacteria. Bacteria build a tough skin of carbohydrate chains, interlocked by short peptide strands, that braces their delicate membrane against the cell's high osmotic pressure. Lysozyme breaks these carbohydrate chains, destroying the structural integrity of the cell wall. The bacteria then burst under their own internal pressure.

Alexander Fleming discovered lysozyme during a deliberate search for medical antibiotics. Over a period of years, he added everything that he could think of to bacterial cultures, looking for anything that would slow their growth. He discovered lysozyme by chance. One day, when he had a cold, he added a drop of mucus to the culture and, much to his surprise, it killed the bacteria. He had discovered one of our own natural defenses against infection. Unfortunately, lysozyme is a large molecule that is not particularly useful as a drug. It can be applied topically, but cannot rid the entire body of disease, because it is too large to travel between cells. Fortunately, Fleming continued his search, finding a true antibiotic drug five years later: penicillin.

Hen egg white has a high content of lysozyme which protects the integrity of the delicate yolk, thus making egg white (albumen), the preferred raw material for industrial production of the Lysozome enzyme.

May be harmful by inhalation or ingestion, or act as an irritant.