Application of a novel phage vB_Sa_2868B2 and its endolysin LytN with broad antibacterial Spectrum against multidrug-resistant Staphylococcus aureus on food matrices, and metal surfaces.

The novel bacteriophage vB_Sa_2868B2 and its endolysin LytN, which were isolated and characterized in this study, demonstrate significant potential as effective biocontrol agents against foodborne multidrug-resistant Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). Morphological and genomic analyses revealed that vB_Sa_2868B2 is a new species of the genus Rosenblumvirus. Lifecycle and stability assays demonstrated that phage vB_Sa_2868B2 exhibited a short latent period (20 min), a high burst size (126 plaque-forming units [PFU]/cell), and broad tolerance to temperature (4-60 °C) and pH (4.0-11.0) conditions. The phage displayed a wide host range for S. aureus, lysing 49.10 % S. aureus strains with 29 different sequence types (STs). vB_Sa_2868B2 effectively reduced bacterial loads of S. aureus in milk by 5.60-5.80 log10 CFU/mL within 6 h. Furthermore, the purified endolysin LytN of vB_Sa_2868B2 showed robust stability across a wide temperature (0-45 °C) and pH (3.0-12.0) range, coupled with excellent metal ion tolerance. Notably, endolysin LytN demonstrated broad lytic activity, lysing 97.13 % of staphylococcal strains spanning 37 distinct STs, particularly including 99.11 % of the methicillin-resistant S. aureus (MRSA) isolates. Both phage vB_Sa_2868B2 and endolysin LytN exhibited significant bactericidal efficacy against MRSA in pork, with LytN treatment achieving a 3.50 log10 CFU/mL reduction. Additionally, the phage and endolysin effectively disrupted biofilms on stainless steel surfaces, reducing bacterial counts on metal contact surfaces by 4.00 and 4.30 log10 CFU/mL. Collectively, these findings highlight that the novel phage vB_Sa_2868B2 and endolysin LytN are highly effective, promising antibacterial biocontrol candidates for controlling S. aureus in the food industry. This work provides a robust foundation for developing novel, phage-based interventions to enhance food safety and combat antibiotic resistance.