Characterization of the Antimicrobial Activity of Lactic Acid Bacteria Isolated from Buffalo Milk in West Sumatera (Indonesia) Against Listeria monocytogenes
Salam N. Aritonang
Background and Objective: Listeria monocytogenes is an important pathogenic bacteria in various cases of poisoning in the food industry due to its ability to grow in cold temperatures and to survive in freezing temperatures. Lactic acid bacteria have important probiotic attributes including their antimicrobial effect against this pathogen. Therefore, this study aimed to isolate lactic acid bacteria from buffalo milk and characterize its antimicrobial activity against Listeria monocytogenes. Materials and Methods: Buffalo milk was collected from four districts in West Sumatera, Indonesia and its composition analysed. A total of 88 lactic acid bacteria strains were isolated and grown at De Man Rogosa Sharpe Agar (MRSA). The strains were identified based on morphology (shape, size and colour) and their biochemical characteristics (catalase test and the fermentation type) and then screened for antimicrobial activity against L. monocytogenes. The species were further identified based on 16S rRNA gene sequence analysis. Results: As a result of isolation and identification, 19 strains of lactic acid bacteria were screened against L. monocytogenes, but only three isolates (A 3.2, A 3.3 and TD 7.2) showed high inhibition against L. monocytogenes. They were identified using 16S rRNA gene sequence analysis. Conclusion: The BLAST results of the identification procedure showed that the isolated bacteria from buffalo milk belonged to Lactobacillus fermentum strain L 23 (A 3.3), Lactobacillus fermentum strain 6704 (TD 7.2) and Lactobacillus oris strain J-1 (A 3.2).
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