Growth Inhibition of Foodborne and Pathogenic Bacteria by Conjugated Linoleic Acid

The influence of conjugated linoleic acid (CLA) on the growth of some foodborne and pathogenic bacteria was examined. A potassium salt of CLA (CLA-K) was tested against three Gram-positive strains (Bacillus cereus, Staphylococcus aureus, and Streptococcus mutans) and five Gram-negative strains (Pseudomonas aeruginosa, Salmonella typhimurium, Vibrio parahemolyticus, Klebsiella pneumoniae, and Proteus mirabilis). CLA-K-mediated growth inhibition was evident for all tested strains, particularly the Gram-positive strains. The IC50 value of CLA-K was 0.3 mM for B. cereus, 1.2 mM for S. aureus, and 0.3 mM for S. mutans, whereas the value was 1.2 mM for K. pneumoniae, 1.2 mM for P. aeruginosa, 1.8 mM for S. typhimurium, 1.8 mM for V. parahemolyticus, and 2.4 mM for P. mirabilis. The CLA-K delayed the growth of all the tested strains at lower CLA-K concentrations, but completely inhibited the growth at higher concentrations. All cells grown in the medium containing CLA-K contained CLA in their membranes and exhib...