High-sensitivity and high-specificity colorimetric detection of viable Staphylococcus aureus in ready-to-eat foods using a temperate-bacteriophage-based system with peroxidase-like activity

Although bacteriophage-based biosensors are promising tools for the rapid, convenient, and sensitive detection of S. aureus in food products, the effect of biosensors using temperate phages as the biorecognition element to detect viable S. aureus isolates remains unclear. In this study, four temperate Staphylococcus aureus phages were isolated, and their biological features were compared. The selected phage, SapYZUs7, was immobilised on an MnCo2O4 nanozyme to prepare SapYZUs7@MnCo2O4, and the application of SapYZUs7@MnCo2O4 in the S. aureus detection was evaluated. Compared to the other three S. aureus phages, SapYZUs7 exhibited a higher titre, broader host range, greater pH tolerance (3-12, > 91 %), higher absorption rate (71.6 %, 6 min), and more unique gene content. The characterisation of SapYZUs7@MnCo2O4 revealed its successful immobilisation, excellent biological activity, and peroxidase-mimicking ability. Moreover, the SapYZUs7@MnCo2O4 exhibited high sensitivity and specificity for the rapid colorimetric determination of viable S. aureus counts, with a limit of detection of 0.77 x 10(2) CFU/mL. In addition, SapYZUs7@MnCo2O4 was successfully employed for the colorimetric detection of S. aureus in food samples, regardless of different food additives, NaCl concentrations, and pH values. In conclusion, the SapYZUs7@MnCo2O4 is a powerful tool for the detection of viable S. aureus in food matrices.