Abstract: In this study,papain was chosen as the hydrolyzing enzyme and the enzymatic hydrolysis conditions were optimized with the inhibitory effect of protein hydrolysate against Staphylococcus aureus as index.The relatively molecular weight distribution of laver enzymolysis liquid showed that laver protein with molecular weight below 1000 Da accounted for 96.68%.The laver protein antimicrobial peptides(LPAP)was purified through DEAE-52 cellulose anion exchange chromatography and Sephadex G-25 gel filtration chromatography,which was identified as a tetrapeptide FFDD(Phe-Phe-Asp-Asp)by Q-TOF-MS.This LPAP possessed a relatively broad spectrum of antibacterial activity,and showed significant growth inhibition against gram-positive bacterials and gram-negative bacterials.Minimum inhibitory concentration of LPAP against S.aureus was 0.25 mg/mL.The electron microscope photos of S.aureus impacted by antibacterial peptides revealed its antibacterial mechanism was mainly due to the destruction of cell membrane.

Key words: laver, protease, hydrolyzate, antimicrobial peptides, purification