Effect of lithium chloride and other inhibitors on the growth ofListeria spp.

Abstract The effect of lithium chloride on the growth of Listeria was studied in enrichment broths to determine optimum levels for this inhibitor. Listeria monocytogenes was able to grow in concentrations up to 2%, but above this level inhibition was noted. Enterococcus faecalis , a major competitive organism, was inhibited by low levels of LiCl. Competitive flora able to grow in the presence of LiCl are normally inhibited by nalidixic acid except for staphylococci. Substrates such as skimmed milk powder do not affect the inhibition of competitors by LiCl significantly. Trypaflavine was shown not to inhibit significantly the Listeria strain studied in the presence of LiCl. The combination of LiCl, trypaflavine and nalidixic acid should be studied further in enrichment procedures for L. monocytogenes .