Streptococcus lactis is a peptide formed by Streptococcus lactis, and its appearance appears as a light brown solid powder. It has different solubility in different pH value, and it is almost insoluble in alkaline environment. Streptococcus lactis can be digested by proteases in the digestive tract and converted into amino acids, providing the body with essential nutrients and energy sources. In addition, studies have shown that lactococcin has the ability to inhibit the growth of most Gram-positive bacteria, bacilli and other pathogenic bacteria, and to kill them. Currently, lactococcin has been widely used as a pure natural preservative in pharmaceutical manufacturing, health food, convenience food, canned food and other medical and food preservation and storage technologies.