Abstract: The present study aimed at improving plantaricin production by Lactobacillus plantarum LPL-1. Fermentation conditions were optimized by response surface methodology (RSM). The inhibitory activity (AU/mL) against Listeria monocytogenes 54002 was used as response variable. Using one-factor-at-a-time method and Plackett-Burman design, temperature, fermentation time and initial medium pH were identified as main factors that influence plantaricin production. The optimal fermentation conditions were determined as 31 ℃, 6.40, 32 h, 0.5% and 60% for temperature, initial medium pH, time, inoculum size and medium volume in flasks, respectively using path of steepest ascent and RSM with Box-Behnken design. The antibacterial activity of plantaricin produced under the optimized conditions was 674.29 AU/mL, which increased by 2.31 times compared with that before optimization. It was also found that the crude plantaricin extracted from the fermentation broth had obvious inhibitory effect on Gram-positive bacteria, and it was stable to heat (100 ℃, 30 min), acid-base conditions (pH 2–10) and sensitive to protease. Meanwhile, the disulfide bonds of bacteriocin were broken by disulfide bond denaturants, which proved the importance of disulfide bonds for bacteriocins. Conclusively, the present study provides insights into the potential use of bacteriocin as a food preservative in the food industry.

Key words: Lactobacillus plantarum LPL-1, plantaricin LPL-1, fermentation conditions, response surface methodology, physicochemical properties