PARTIAL CHARACTERIZATION OF ANTILISTERIAL COMPOUNDS PRODUCED BY NATIVE LACTIC ACID BACTERIA

Objective. Characterization of antilisterial compounds produced by native lactic acid bacteria. Materials and methods. Lactic acid bacteria (LAB) were isolated from 42 samples collected from foods and food processing equipment. Identification of LAB species was assessed by biochemical reactions. The antilisterial activities of the isolates were tested against 17 L. monocytogenes strains belonging to 4b, 4e and 3b serotypes, by the agar differed spot on the lawn technique. Crude extracts were subjected to catalase, proteinase K, hydrochloric acid and high temperature (95ºC and 121ºC) treatments in order to characterize the antilisterial compounds. The molecular weights were estimated by SDS-PAGE and bioassays were performed. Results. Seventy five strains were identified out of 250 lactic acid bacteria isolates. The inhibitory compounds produced by LAB displayed dissimilar activities against the different L. monocytogenes strains. Furthermore, three native isolates identified as Lactobacillus spp., Leuconostoc spp. and Enterococcus spp. showed improved antilisterial effect due to the production of compounds with molecular weight below 7600 Da. Conclusions. We demonstrated the presence of native lactic acid bacteria with potential as biocontrolers in foods distributed in Colombia.