Bacteriocin potency test of lactic acid bacteria (LAB) isolated from rumen of Bali cattle against low pH and bile salt

Background: Lactic acid bacteria (LAB) are a group of probiotic bacteria, which are not at risk and can even have a positive impact on human and animal health. As a source of probiotics, the application of these bacteria must be resistant to environmental conditions such as resistance to low pH and gastrointestinal bile acids. This study aimed to determine the probiotic potential of lactic acid bacteria isolated from the rumen and colon of Bali cattle by testing their resistance to low pH and bile salts.Methods: The study began with the cultivation of isolates from the rumen and colon of Bali cattle including growth on liquid MRS media, catalase test, and Gram staining. The second stage involved testing the isolate's resistance to low pH (pH 2, 3, and 4) and testing NaDC with concentrations of 0.2 mM, 0.4 mM, and 0.6 mM.Results:Tests showed that of the 10 isolates from Bali cattle rumen tested, it was found that all had high tolerance at low pH, namely growing well at pH 2 and NaDC levels up to 0.6 mM. The results obtained corroborate the results of previous studies on the resistance of lactic acid bacteria isolates from the gastrointestinal tract of Bali cattle to low pH and bile salt levels as a condition for application as a probiotic.Conclusion: The resistance of the isolate to low pH and NaDC shows that LAB isolates from the rumen of Bali cattle have the potential to be used as a reliable source of probiotics.