Probiotics are non- pathogen living microorganisms which express beneficial effects on host, when are administered in adequate amounts. The present study was undertaken to isolate and characterize certain lactic acid bacteria (LAB) isolate which could be used as a probiotic
LAB was isolated by culturing the samples on MRS agar. The isolates were screened for their probiotic potential using in-vitro tests, including tolerance to acid and bile, survival in simulated gastrointestinal tract conditions, and hemolytic activity as well as antibiotic susceptibility. In addition, antibacterial activity of the isolated strains against E. coli O157 and Salmonella enterica was determined.
Lactobacillus delbruekii ssp. lactis showed the highest tolerance to low pH, bile and simulated gastrointestinal tract conditions. This strain exhibited resistance to Nalidixic acid, Cloxacillin, Aztreonam and Colistin as well as effective antibacterial activity against two Gram negative pathogens, lacking hemolytic activity. Finally, the strain was identified as Lactobacillus delbruekii ssp. lactis using biochemical characterization and 16S rRNA sequencing assay.
Discussion and conclusion: In the present work, a potentially probiotic was Lactobacillus delbruekii ssp. lactis isolated from dairy product (Qarish Cheese). The bacterium displayed good probiotic properties.