An Electrochemical Biosensor for the Detection of Bacteriophage of Lactococcus Lactis

The bacterial activity of Lactococcus lactis is exploited in the dairy industry for the fermentation of milk. However, the spreading of phages of L. lactis prevents the proper lactic fermentation, causing economic losses and waste. This work aims to explore an electrochemical detection method for the fast and reliable monitoring of the presence of the L. lactis phages. The detection is based on electrochemical biosensor with live L. lactis bacteria covering the sensor electrodes, whose electrical response is measured by electrochemical impedance spectroscopy (EIS). Solutions contaminated by phages induce bacteria lysis, clearly reducing the bacteria coverage over the electrodes and leading to evident parametrical shifts in the charge transfer resistance. Screen-printed and interdigitated sensors were tested to identify the most stable electrode suitable to work with the lab solutions. Experimental measurements with laboratory contaminated ideal samples show that the screen-printed sensors with gold and silver electrodes have great stability, reproducibility, and detection capability. Electrochemical results evidence great decreases of the charge transfer resistance in phages contaminated sensors in lab environments, paving the basis for the development of a new electrochemical biosensor capable of detecting the L. lactis phages.