Epsilon-Polylysine is a natural polycationic biopolymer produced commercially through aerobic fermentation of Streptomyces albulus. Its antimicrobial mechanism involves electrostatic interaction of its cationic amino groups with the negatively charged bacterial cell membrane, leading to membrane disruption, leakage of intracellular contents, and cell death.
Unlike chemical preservatives, it is a peptide that is ultimately metabolized as a protein in the body. It is approved for food use in Japan (since 1989), China (GB 2760), South Korea, and the US (FDA GRAS Notice GRN 000135). The effective use concentration is very low (10–500 ppm), and it is stable across a wide pH range (3–9) and retains activity after autoclaving at 120°C for 20 minutes, which is exceptional among natural preservatives.