Evaluation of <i>Lactiplantibacillus plantarum</i> C07 Isolated from Fermented Whey: Insights into Antimicrobial Properties and Its In Situ Biopreservative Application in Chinese Rubing Cheese

A strain of <i>Lactiplantibacillus plantarum</i> (<i>L. plantarum</i>) C07 was isolated from the fermented whey of Chinese Rubing Cheese (CRC). This strain demonstrated significant antibacterial activity against multidrug-resistant <i>Staphylococcus aureus</i> DC.RB-015, with an inhibition zone measuring 19.83 ± 0.99 mm. At a concentration of 1 × MIC, it inhibited cell growth and reduced biofilm formation by 66.23%. The strain exhibited sensitivity to antibiotics such as chloramphenicol and showed both acid resistance and biosafety. Genome and ultrahigh-performance liquid chromatography coupled with quadruple exactive mass spectrometry (UHPLC-QE-MS) metabolomics analyses revealed that its core antibacterial substances were lactic acid (C₃H₆O₃) and indole-3-lactic acid (C₁₁H₁₀NO₃, ILA), which synergistically inhibited peptidoglycan synthetases (MurC, MurD, MurE, MurF, and MurG) through hydrogen bonding, thereby disrupting cell wall formation. A 7-day biological control experiment confirmed that the bacteria could effectively inhibit foodborne pathogens in Chinese Rubing cheese at varying storage temperatures, providing a theoretical basis and practical insights for the development of biological preservatives derived from cheese and fermented foods to combat foodborne pathogens.