Antibacterial activity of lactobacilli from meat

To highlight the role of lactic acid bacteria in meat safeguarding, bacteria from various types of local red meats (Annaba- Algeria) preserved under various conditions were isolated and characterized. Isolation was limited to lactobacilli and some types of spoilage and pathogenic bacteria. The characterization of the isolated strains was done by means of physiological and biochemical identification tests. Various methods were considered to characterize the antimicrobial activities of the 29 isolated lactobacilli strains from 19 samples. The results revealed that the isolated lactobacilli strains produce and excrete in the culture medium substances showing important inhibiting activities towards Gram positive and Gram negative bacteria. These activities are due to various molecules, but varied according to the lactobacilli and the considered bacteria. Inhibition by lactic acid and H2O2 was observed for the Gram+ and the Gram-, except for Pseudomonas. Bacteriocin inhibition was especially observed for the Gram+, while among the Gram-, only Salmonella was inhibited. Bacteriocin activity towards S. aureus was confirmed for eight strains of lactobacilli, resulting from standard thermostable extracellular proteins for six of them. This study shows that the isolated lactobacilli present important antibacterial activities, which suggested that they can be used for a better conservation of fresh meat, in order to preserve its microbiological quality; since they are already widely used in Europe for the fermentation of meat products like dry sausage.