Proteolytic and Antimicrobial Activity of Indigenous Probiotic Lactic Acid Bacteria Isolated from Traditional Cheese Samples

Introduction and Objectives: Lactic acid bacteria (LAB) are extensively used in dairy products where they bestow desirable effects on the taste, odor, texture and flavor of the product. The proteolytic activity of the LAB is known to be responsible for the release and generation of biological peptides, including hypotensive peptides which inhibit angiotensin I-converting enzyme (ACE), opioid agonist and antagonist peptides, and mineral binding, immunomodulatory, antibacterial, and antithrombotic peptides The aim of the present study was to screen the LAB isolated from cheese sample for their probiotic properties. The isolates were also screened for their proteolytic and antimicrobial activity. Materials and Methods: Twenty-one LAB isolated from 9 cheese samples were identified to genus and species level by biochemical and molecular methods. The isolates were tested for their pH, and bile tolerance and antibiotic sensitivity profile. The antimicrobial potential of the isolates against a number of gram positive and gram-negative pathogens was determined by agar well diffusion and Agar spot assay. The isolates were screened for their ability to produce protease on skim milk agar plate. Results: L.casei, L.acidophilus and L.plantarum isolated from the cheese samples potential probiotic properties by demonstrating acid and bile tolerance. The selected isolates showed significant antibacterial activity. S.aureus was the most sensitive indicator strain while none of the isolates inhibited the growth of Shigella dysenteriae. Significant proteolytic activity was demonstrated by 12 of the isolates, while L.plantarum showed the strongest proteolytic activity on the tested media. Conclusion: The results of this study concludes that dairy LAB isolates have probiotic potential and are significant protease producers with strong antimicrobial actions. Therefore, these isolates might have the potential to be used in therapeutics and as food bio-preservatives.

کلیدواژه ها:

lactic acid bacteria ، probiotic ، Proteolytic activity ، Antimicrobial Activity ، cheese.