... highly efficient, safe, and has no side-effects. Poly-L-lysine (ε-poly-L-lysine, EPL) is a small natural homopolymer of the essential ... amino acid L-lysine that is produced by bacterial fermentation. ε-Poly-L-lysine is used as a natural preservative ... soluble in ethanol, insoluble in organic solvent such as ethyl acetate, ether, ect.. Its activity is not affected by PH, ...