Assessment of the susceptibility of lactic acid bacteria to biocides

Biocides are antimicrobial compounds that are widely used in the food industry and medical environments. In this study, we determined the Minimum Inhibitory Concentrations (MICs) by the microdilution method of four different biocides for a large collection of LAB of different origins. The tested isolates belong to 11 species of the Lactobacillus genus and to Streptococcus thermophilus, Streptococcus salivarius and Lactococcus garvieae. The results obtained in this study indicate that low susceptibilities to benzalkonium chloride (BC), triclosan (Tr), chlorhexidine (Ch), and sodium hypochlorite (SH) are not frequent among LAB. Moreover, no systematic co-tolerance between two or more tested biocides was found; that is, strains displaying high MIC values and thus low sensitivity to one of the biocides did not show higher MIC values for the other biocides.