Camel-derived Lactiplantibacillus plantarum LP-170 as a natural antimicrobial solution to combat multidrug-resistant Staphylococcus aureus in dairy products

Foodborne pathogens, particularly multidrug-resistant (MDR) Staphylococcus aureus, present a substantial threat to public health through the food chain. In this study, Lactiplantibacillus plantarum LP-170 was isolated from camel feces, and its cell-free supernatant (CFS) exhibited remarkable antibacterial activity against both standard S. aureus ATCC 29213 and MDR S. aureus strains isolated from contaminated milk. The CFS of LP-170 demonstrated maximum inhibition zone sizes of 20.21 ± 0.21 mm in agar well diffusion assays. Furthermore, the CFS maintained strong antibacterial activity across a broad pH range (3.0-6.0) and at temperatures up to 60°C. Biofilm inhibition assays revealed a dose-dependent suppression of biofilm formation, as confirmed by confocal laser scanning microscopy. Complete biofilm disruption was observed at concentrations ≥1× the minimum inhibitory concentration. Genomic and metabolomic analyses identified lactic acid, hydroxy fatty acids, and phenolic compounds as key antibacterial metabolites. These metabolites synergistically disrupted bacterial membranes, induced oxidative stress, and inhibited biofilm formation. Additionally, the CFS significantly reduced S. aureus contamination in milk samples stored at temperatures of 4°C, 25°C, and 35°C, achieving bacterial reductions of up to 4.6 log cfu/mL. These findings underscore the potential of LP-170 as a natural antimicrobial agent to mitigate MDR S. aureus contamination in dairy products, thereby contributing to enhanced food safety.