Inhibitory activity of a novel antibacterial peptide AMPNT-6 from Bacillus subtilis against Vibrio parahaemolyticus in shrimp

Vibrio parahaemolyticus is a major foodborne pathogen in marine products. Effective methods for reducing V. parahaemolyticus in seafood would reduce the likelihood of foodborne outbreaks of Vibrio. AMPNT-6 is a novel antibacterial peptide secreted by Bacillus subtilis NT-6 isolated from Natto, a Chinese traditional fermented-soybean paste. The objective of this study is to investigate the antibacterial activity of AMPNT-6 against V. parahaemolyticus. The disc diffusion experiment indicated that AMPNT-6 posed an evident inhibitory activity against V. parahaemolyticus with a diameter of 15.5 mm and the MIC was measured at 1.25 mg/mL. Compared to the control, the significant bactericidal activity was observed through the changes of V. parahaemolyticus growth curve and inactivation kinetics when the final concentration of AMPNT-6 in bacterial suspension was added to 1 and 2 MIC. Furthermore the significant reduction of population size of V. parahaemolyticus in shrimp matrix was also found when the final concentration of AMPNT-6 reached to 2 MIC. These obtained results indicate that AMPNT-6 can potentially be used as a natural inhibitor to control V. parahaemolyticus borne on shrimp matrix. ► AMPNT-6 posed inhibitory activity with zone diameter of 15 mm ► MIC was measured at 1.25 mg/mL. ► The reduction of population size in shrimp was 2 MIC AMPNT-6.