Antibacterial mechanism of garviecin LG34 against S. aureus and L. monocytogenes and its application in dairy products preservation

Abstract

Abstract Purpose The objective of this paper was to identify the antibacterial mode of garviecin LG34 against S. aureus and L. monocytogenes and the inhibitions on these two food-borne pathogenic bacteria in dairy products.Methods Antibacterial mechanism of garviecin LG34 was identified by the effects on the efflux of Potassium (K+) ions, extracellular electrical conductivity, UV-absorbing substances, potential across the membrane (ΔΨ) and cell permeability. The inhibitions of garviecin LG34 against S. aureus and L. monocytogenes in milk was studied by plate colony counting method.Results Supplementation with 160 AU/ml of garviecin LG34 had a bactericidal effect on these two bacteria. 160 AU/ml of garviecin LG34 resulted in the effusion of potassium ion and UV-absorbing substances, the leakage of cellular electrolytes and the dissipation of electrical potential across the membrane of these two food-borne bacteria. Moreover, the increase in cell permeability of both strains was observed by flow cytometer after cells treated with 160 AU/ml of garviecin LG34. Garviecin LG34 significantly inhibited the growth of these two food-borne bacteria. in the dairy products especially in skim milk.Conclusion Garviecin LG34 could cause pore formation, intracellular materials release and permeability increase of S. aureus and L. monocytogenes, and may be applied to dairy products as bio-preservative.