Screening of technological and probiotic properties of lactic acid bacteria isolated from Algerian traditional fermented milk products

A total of 208 strains of lactic acid bacteria (LAB) were isolated from Algerian traditional fermented milk (Jben, Klila, Raib and Lben), in order to evaluate their technological and probiotic properties. These strains were tested for their antimicrobial activity against Listeria monocytogenes using agar well diffusion technique. Only 11 strains were retained, they were also characterised in respect to their technological properties. The retained strains were identified by analyses of the 16S rDNA gene as; Lb. curvatus (1 strain), Ln. mesenteroides subsp mesenteroides (1 strain), Lb. plantarum (3 strains), Lb. brevis (2 strain), Lactobacillus acidophilus (2 strains), and Lactococcus lactis subsp lactis (2 strains). All the antimicrobial compounds produced by the selected lactic acid bacteria were fully or partially inactivated by the proteolytic enzymes. The compounds were heat stable up to 100°C for 20 min, and were active from pH 3.0 to 10.0. The enzymatic potential of the strains evaluated with API ZYM system show that all strains exhibited high leucine, cystine aminopeptidase and β-Galactosidase activities. Lactococcus strains were those that showed the greatest degree of proteolytic activity, however very low lipolytic and amylolytic capacity was detected for same strains. Two out of the 11 selected strains showed moderate survival rates under simulated gastric, however all tested strains showed a high stability under intestinal conditions. According to the results, the selected LAB strains could be used as potential probiotics to a possible inhibition of food-borne pathogenic bacteria and also would be of considerable interest to use as starter culture.