Nouna SabahSaidane NassimaEncadreur: THABET .R.2024-07-162024-07-162012579/112-MB PDFhttp://dspace.univ-khenchela.dz:4000/handle/123456789/6019Abstract A total of 13 strains of lactic acid bacteria isolated starting from a traditionally fermented product (jben) was identified on the basis of some number of morphological, biochemical and physiological criteria. The identification as of these strains revealed the presence of too genera: Lactobacillus (77%), Lactococcus (23%). The screening of these 13 bacterial isolates for the production of antibacterial activities of the jben allowed us to select 3 bacterial strains producers of bacteriocins they were the strains (Lactobacillus plantarum ST2, Lactobacillus acidophilus TH1 and Lactococcus lactis Subsp. Lactis LCL2). The research of bacterial antagonism was carried out according to the method of double-layers and the method of wells diffusion agar under conditions that eliminate the effect of the lactic acid and hydrogen peroxide. In addition, we highlighted the experimental conditions that eliminate the effect of the lactic and hydrogen peroxide. In addition, we highlighted the experimental conditions to determine the spectrum of activity. The strains bacteriocin-producing and its bacteriocins show a potentiality in the fight against the majority of the indicator bacteria tested (Gram+) in food systems particularly in the elaborate jben traditionally under uncontrolled hygienic conditions.frThesis