Antibacterial activity of Lactobacillus sake isolated from dry fermented sausages

Lactic acid bacteria isolated from Spanish dry fermented sausages were screened for antagonistic activities under conditions that eliminated the effects of low pH and hydrogen peroxide. From 720 isolates tested 119 were inhibitory to Lactobacillus fermentum CECT285. The isolates showing the largest inhibitory activity exhibited an antagonistic effect against several other lactobacilli and the selected foodborne pathogens Staphylococcus aureus and Listeria monocytogenes. Comparison of the antimicrobial spectra of the supernatants suggested that the inhibitory compounds were not identical. The isolates were tentatively characterized as Lactobacillus sake. One of the isolates, L. sake 148 was chosen for further study. The compound excreted by L. sake 148 was active against various lactobacilli and several Gram-positive foodborne bacteria, but not against the Gram-negative bacteria tested. The antagonistic effects were almost eliminated by treatment with proteases, whereas they were heat resistant and bacteriostatic rather than bacteriocidal.