Abstract: This paper used spermatozoa of adult squid as crude material, through a serial processes of extraction, crude productof protamine was yielded and measured the minimum inhibition concentration of squid protamine on E.coli and S.aureus. Theground flesh of fish was added with protamine. In this paper, pH value, inorganic, organic substances and other chemical componentsthat affect antibacterial activity of protamine were studied. The results indicated that protamine was an effective natural foodpreservative.

Key words: protamine, minimum inhibitory concentration (MIC), antibacterial action