Antibacterial Effects of Synthetic Plantaricins Against Staphylococcus aureus

<b>Background/Objectives:</b> Plantaricins without a signal sequence were synthesized based on bacteriocins, plantaricins A, E, F, J, and K, of <i>Lactiplantibacillus plantarum</i> KM2. The antibacterial activities of four combinations of synthetic plantaricins-spPlnA, E&F, E&J, and J&K-were identified against <i>Staphylococcus aureus</i> ATCC 12692. And in this experiment, we aimed to identify the antimicrobial mechanism of the synthesized plantaricin sample against <i>S. aureus</i>. <b>Methods/Results:</b> The minimal inhibitory concentrations for each combination were 1.4 μg/mL, 1.8 μg/mL, 1.6 μg/mL, and 1.6 μg/mL, respectively. Raman spectra changed after treating <i>S. aureus</i> ATCC 12692 with synthetic plantaricins. Furthermore, transmission electron microscopy results revealed that the four synthetic plantaricin combinations could induce the cell lysis of <i>S. aureus</i> ATCC 12692. Finally, the four synthetic plantaricin combinations maintained their antibacterial effect at temperatures below 40 °C, and at pH levels of pH = (4-7). Except for spPlnJ&K, they are stable against the action of α-amylase and lysozyme. Overall, these results indicate that, excepting spPlnJ&K, the three synthetic plantaricin combinations exhibit similar antibacterial activity. <b>Conclusions:</b> Through this study, we confirmed that synthetic plantaricin exhibited antimicrobial activity against <i>S. aureus</i>, demonstrating its potential as a direct antimicrobial agent. However, since the antimicrobial activity decreased due to protease, it was confirmed that its use is limited in environments where protease is present.