Plantaricin LD1 Inhibits the Growth and Biofilm Formation of Staphylococcus aureus in Milk

Abstract

Background and objectives:The contamination of food by spoilage microorganisms is a major concern for public health. Food-borne pathogens are commonly encapsulated by biofilms. Bacteriocins of probiotic lactic acid bacteria, such as nisin and pediocin have been used as bio-preservatives to improve food safety and extend the storage period of some food types. Therefore, there is a need to explore the potential of bacteriocins to impede the growth and biofilm formation by food spoilage bacteria in milk.Methods: Plantaricin LD1 was purified from a potential probiotic, Lactobacillus plantarum LD1. Antimicrobial and anti-biofilm activity was then determined against a food-borne pathogen, Staphylococcus aureus subsp. aureus ATCC 25923. The efficacy of plantaricin LD1 against S. aureus subsp. aureus ATCC 25923 was also tested in the milk.Results: Plantaricin LD1 had a minimum inhibitory concentration of 79.16 µg/mL and minimum bactericidal concentration of 158.33 µg/mL against S. aureus subsp. aureus ATCC 25923. Biofilm formation of S. aureus subsp. aureus ATCC 25923 was completely inhibited in the presence of 79.16 µg/mL of plantaricin LD1. Complete loss of cell viability in milk was observed after treatment with double minimum inhibitory concentration (158.33 µg/mL) of plantaricin LD1 at 48 hrs. Conclusions:Our findings illustrate the antimicrobial and anti-biofilm activity of plantaricin LD1 against S. aureus subsp. aureus ATCC 25923 in milk. These results suggest that plantaricin LD1 can be used as a natural preservative to expand the shelf-life of milk.