Antimicrobial and Antioxidant Properties of Natural Postbiotics Derived from Five Lactic Acid Bacteria

The application of natural antimicrobial and antioxidant agents in food and pharmaceutical products has recently become a trend due to the high demand for them from consumers. Postbiotics are bioactive compounds that are produced when the healthy bacteria in the gut ferment fiber.

This study aimed to compare the antibacterial and antioxidant properties of postbiotics from 5 different lactic acid bacteria (LAB) including Lactiplantibacillus fermentum, Lactiplantibacillus plantarum, Lactiplantibacillus rhamnosus, Lactobacillus casei, and Lactobacillus acidophilus.

Two different methods were adopted to obtain postbiotics (M1 and M2). M1 was the simple method in which the centrifugation was employed while in M2 method, ethyl acetate was used to obtain postbiotics. Agar disc diffusion, minimum inhibition concentration, and minimum bactericidal concentration were used to assess the antimicrobial activity of postbiotics. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) test was performed in order for investigating the antioxidant property.

The best results were recorded for L. casei compared to other LABs. Highest values of the agar disc diffusion method were obtained for L. casei. The inhibition zones for Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus, for examples, were 22 mm, 20 mm, and 19 mm, respectively. The postbiotic of L. casei also exhibited the most potent antioxidant activity among other probiotic bacteria. The data showed that M2 was a more effective method than the other method for acquiring postbiotics.

It was recommended LABs postbiotics should be applied as antioxidant, antimicrobial, and preservatives in food and pharmaceutical industries due to their desired effects and natural characteristics.