Antagonistic Effects of Some Lactobacilli On Some Gram-Negative Bacteria

Three lactobacilli strains were examined for the inhibitory activity against some gram-negative bacteria with a comparison of well diffusion and spot on lawn method. The inhibitory activity of lactobacilli under spot on lawn method showed significant clear zones. Although in spot on lawn method, lactobacilli have strongest antagonistic activity against P. aeruginosa ATCC 27853, in well diffusion method, it was the least sensitive tested bacteria. In spite of E. coli O157:H7 is inhibited secondly in well diffusion method (16mm), the value of the inhibition is lower than spot on lawn method (26mm). These results showed that spot on lawn method is better method than well diffusion method. Key Words: Antagonism, Gram-negative bacteria, Lactic acid bacteria, Spot on lawn method, Well diffusion method