Screening, Isolation and Identification of Lactic Acid Bacteria From a Traditional Dairy Product of Sabzevar, Iran

Background: Lactic acid bacteria (LAB) are a major group of probiotics. Isolation of these bacteria is difficult, because they have a complex ecosystem in fermented dairy products. Objectives: The aim of this study was to detect Lactobacillus and Lactococcus in a conventional dairy product (Khameh) and study their probiotic characteristics. Materials and Methods: To isolateLAB, samples were collected from four different villages. Afterwards, screening was performed in pH = 2.5. The selected strains were examined for their tolerance to acidic pH (3) and 0.3% bile salt. Moreover, the antimicrobial activity of the isolated strains against two pathogenic bacteria, Salmonella typhimurium and Staphylococcus aureus, was assessed using the disc plate method. Finally, the selected strains were identified by polymerase chain reaction (PCR) screening and sequencing. Results: Among the isolated samples, two strains (Lactobacillus and Lactococcus) were highly resistant to unfavorable conditions and the L1 strain showed the highest antimicrobial activity. Conclusions: This study showed that the conventional dairy product (Khameh) contained probiotic bacteria, which are capable of fighting against pathogenic bacteria and living in the digestive tract.