Anti-bacterial activity of Lactobacillus plantarum isolated from Algerian raw gaot’s milk against Staphylococcus aureus

The food contamination is a major problem for the consumer especially during the summer period in the hot countries. The bacterial interactions exploitation is a new strategy to fight against these pathogenic microorganisms. The objectif of this study was to characterize Lactobacillus sp isolated from raw goat's milk which can produce an anti-microbial substance toward the growth of Staphylococcus aureus. The microbiological and biochemical methods were used to identify the isolates of lactic acid bacteria which have an antimicrobial activity. Nine isolates of lactic acid bacteria were identified and belonging to Lactobacillus species. The dominant species are: Lb. rhamnosus, Lb. plantarum, Lb. casei, Lb. paracasei subsp. paracasei, Lb. acidophilus, Lb. delbrueckii subsp. lactis, Lb. fermentum, Lb. paraplantarum and Lactobacillus sakei subsp. sakei. The study of the interactions revealed the capacity of three strains Lb. plantarum (58), Lb. paracasei subsp. paracasei (55) and Lb. rhamnosus (68) which can inhibite Staphylococcus aureus. In mixed culture with Lb. plantarum the growth of Staphylococcus aureus was 1.6 log cfu/ml after 12 h and no growth was observed after 72 h of incubation. The chemical characterization of inhibiting substance of Staphylococcus aureus revealed the protein nature.