Potent bactericidal effects of bicarinalin against strains of the Enterobacter and Cronobacter genera

Bicarinalin is a linear and C-terminus amidated cationic peptide characterized from the Tetramorium bicarinatum ant venom. In the present study, the antibacterial activity of bicarinalin against four representative strains of Enterobacter genus and Cronobacter sakazakii, emerging opportunistic pathogens in foods, was evaluated in laboratory conditions. The lowest minimal inhibitory and minimal bactericidal concentrations were obtained on C. sakazakii, while the highest values were found on Enterobacter cloacae. Whatever the microorganism, bicarinalin was more potent than melittin, ampicillin and tetracycline. SYTOX green nucleic acid staining was used to assess the effect of bicarinalin on bacterial membrane integrity. In all strains, permeabilization of the membrane was observed for sub-MIC values, indicating that bicarinalin efficiently disrupted the plasma membrane leading to the bacterial death. Collectively, these data suggest that this natural peptide could be used for enhancing the microbial safety of food and prevent the microbial spoilage of diverse biological matrices by Enterobacteriaceae.