Abstract: The strain F9, which can produce antibacterial substances, was isolated from the Pinctada fucata mucus and finally identified as Lactobacillus coryniformis by 16S rDNA sequence analysis. The antimicrobial spectrum of strain F9 was investigated with agar diffusion method. The results show that the antimicrobial activity of the supernatant is not due to the existence of hydrogen peroxide and organic acid in the solution, and can significantly inhibit various common foodborne pathogens such as Staphyloccocus aureus. It is inferred that the antibacterial substances are proteins with molecular weight of 5~10kDa based on ultrafiltration analysis and protease hydrolysis.