Molecular Isolation, Probiotic Property, and Bacteriocin Production of Enterococcus faecium (TM81) and Lactobacillus curvatus (TM51) with Anti-Listerial Activity in Native Dairy Products of Iran

Lactic acid bacteria in dairy products are the important bacteriocin-producing group with antibacterial activity effect. The aim of this study was the isolation and molecular identification of bacteriocin-producing enterococci and lactobacilli with a wide range of antibacterial activity. Bacteriocin-producing bacteria were isolated and purified from Iranian native dairy products. The effect of bacteriocins on the Gram-negative and Gram-positive indicator strains, as well as the impact of proteolytic enzymes, pH, and temperature changes on bacteriocin production, were investigated. A total of 431 bacteriocin-producing isolates were characterized from 100 traditional cheese and yoghurt samples. The resulting bacteriocin reduced the growth of these two strains. E. faecium TM81 had both bactericidal and bacteriostatic properties, whereas the L. curvatus TM51 only had bacteriostatic properties. The bacteriocin produced by both strains had the highest antibacterial effect among Gram-positive indicator strains such as Listeria monocytogenes and Bacillus cereus. Because produced bacteriocin (resistant to temperature and pH changes) has a wide range of inhibitory spectra on Gram-positive and Gram-negative bacteria especially pathogenic bacteria, it is recommended to use it as a bio preservative in the food/pharmaceutical industry, and animal feed, as well as an alternative to chemical antibiotics.