Herein, a lactic acid bacterium which produces bacteriocin was isolated from malted barley. The isolated strain was identified by 16 S rRNA analysis and designated Leuconostoc citreum HW02. Bacteriocin HW02 was shown to have growth inhibition against health-threatening Gram-positive microorganisms such as Staphylococcus aureus, Listeria monocytogenes, and Latilactobacillus curvatus. Bacteriocin HW02 was reported to be incapable of inhibiting the growth of health-threatening microorganisms after treatment with proteolytic enzymes; thus, it was indicated that bacteriocin is proteinaceous in nature. Bacteriocin HW02 showed stability against a broad range of temperatures (60-121 °C), pH (2-10), various detergents, or organic solvents. Its antimicrobial activity against the indicator strain, Lactiplantibacillus plantarum NCDO 955, was maximised (320 AU mL À1 ) midway through the stationary phase at 12 h. The crude bacteriocin HW02 molecular weight was estimated to be about 7.7 kDa. After the treatment of the indicator strain with bacteriocin, the maintenance of the optical density of the culture, the morphological analysis of cell-structure abnormalities, and cell shrinkage implied that bacteriocin showed bactericidal activity.

Staphylococcus aureus frequently produces biofilm and causes human infections associated with the ingestion of contaminated food. Based on the acknowledgement that the antibiofilm agents for methicillinresistant S. aureus (MRSA) have not been developed yet, this study investigated the potentiality of the JM01 bacteriocin produced by Pediococcus acidilactici JM01 as an effective antibiofilm agent for MRSA. To investigate the antibiofilm activity of bacteriocin JM01 and its mechanism, antibacterial and antiadhesive property assays were performed against MRSA. The effect of JM01 bacteriocin on MRSA biofilm formation was examined by crystal violet staining, the 2,3-bis-[2-methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5-carboxanilide reduction assay and scanning electron microscopy analysis. The inhibition effect of JM01 bacteriocin on MRSA growth was examined by spot plate assay and spectrophotometry. Confocal laser scanning microscopy and the bicinchoninic acid method were conducted to determine the adhesion of JM01 bacteriocin for preventing MRSA adhesion to the polystyrene surface. The results revealed that JM01 bacteriocin significantly reduced the biofilm formation of MRSA by inhibiting its growth and adhesion to a polystyrene surface. These results demonstrate that JM01 bacteriocin could be a potential candidate for the regulation of biofilm formation by MRSA.

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