Isolation and identification of novel antibacterial peptides produced by Lactobacillus fermentum SHY10 in Chinese pickles

The aim of this study was to isolate and identify antibacterial peptides (ABPs) produced by lactic acid bacteria (LAB) in Chinese pickles. The cell-free supernatant collected from the culture of LAB with antibacterial activity against Staphylococcus aureus was used to purify ABPs. A total of 14 strains of LAB were found to have antibacterial activity. Among them, Lactobacillus fermentum (L. fermentum) SHY10 exhibited the most effective antibacterial activity. The antibacterial activity of cell-free supernatant reached the highest level after 20 h of L. fermentum SHY10 culture. Three novel ABPs were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In particular, the NQGPLGNAHR peptide showed antibacterial activity with an IC50 value of 0.957 mg/mL. In addition, molecular docking analysis revealed that this peptide interacted with DNA gyrase and dihydrofolate reductase by salt bridge formation, hydrogen bond interactions, and metal contact.