Isolement et caractérisation des bactéries lactiques à partir des sources laitières naturelles et le rôle antagoniste vis-à-vis des souches pathogènes

Abstract

Lactic acid bacteria have long held a prominent place in the agro-food industry. In this study, we isolated lactic strains from two raw milk samples (goat and camel) from the regions of Laghouat and Mostaganem, which allowed us to obtain 14 Gram-positive and catalase-negative strains. Our research focused on studying the antagonism of lactic acid bacteria isolated from raw camel and goat milk against pathogenic bacteria. Through various microbiological and biotechnological techniques, we identified fourteen strains belonging to the following genera: Lactobacillus delbrueckii (3) Lactobacillus fermentum (1) Streptococcus thermophilus (6) Enterococcus faecium (1) Lactococcus lactis subsp. (3) The results of the technological tests show that these strains are suitable for use in the food industry, exhibiting good proteolytic and lipolytic activity, as well as optimal growth and acidification in skimmed milk at 30°C. The study of the antagonistic effect of bacteriocin-producing lactic acid bacteria, using the well diffusion method, against three reference strains Pseudomonas aeruginosa ATCC27853, Klebsiella pneumoniae ATCC700603, and Proteus mirabilis ATCC35659, revealed positive and significant results for all lactic isolates.