Bacteria-Based Biosensor for the Detection of Lactococcus Lactis Bacteriophage in Agrifood Industry

This letter explores and clarifies the sensing mechanism of a proposed biosensor designed for the rapid detection of the phages of Lactococcus lactis in milk-based solutions. A dedicated experimental test revealed that the increased charge transfer resistance visible when L. lactis proliferates in solution results from both bacterial electrode coverage and direct bacterial interaction with redox species, most likely related to Fe(CN6)3- consumption during L. lactis metabolism. Finally, the evaluation of biosensor performance through impedance phase shift analysis at 100 Hz offers a simplified approach for practical applications. The biosensor demonstrates efficient phage detection within 4 h with detection capabilities for phage concentrations >103 PFU/mL, and future work aims to validate its on-field applicability in authentic milk samples.