Rapid and sensitive colorimetric detection of viable Staphylococcus aureus cells using a bacteriophage-based platform with nanozyme in food

Staphylococcus aureus is an important foodborne pathogen responsible for severe food poisoning. Thus, a rapid, easy-to-perform, and sensitive method is required to screen for S. aureus in ready-to-eat food samples. In this study, we constructed a colorimetric biosensor based on a CuCo₂S₄ nanozyme with excellent peroxidase activity and the bacteriophage SapYZU01 with attractive properties. We further evaluated its applicability in the rapid and sensitive detection of S. aureus in ready-to-eat food samples (braised beef with potatoes, teriyaki chicken, stir-fried pork, steamed duck with mushrooms, and black pepper beef). The SapYZU01@CuCo₂S₄ system detected S. aureus in 14 min total detection time (2 min incubation + 12 min reaction), with a detection limit of 78 CFU/mL. Its reliability and accuracy in S. aureus detection were confirmed and unaffected by interfering bacteria or food components in ready-to-eat food samples. In the proposed method, S. aureus blocks nanozyme active sites of SapYZU01@CuCo₂S₄, reducing ·OH production. In addition, the phage SapYZU01 acted as a biorecognition element, showing excellent specificity for S. aureus recognition. This was due to special binding between receptor-binding protein (RBP) and wall teichoic acid (WTA). Therefore, SapYZU01@CuCo₂S₄ is an effective alternative for quantifying viable S. aureus strains in the food industry.