Electrochemical biosensor based on genetically engineered bacteriophage T7 for rapid detection of Escherichia coli on fresh produce

Foodborne illnesses resulting from bacterial pathogens pose an increasing threat to human health worldwide. The ability to more rapidly and sensitively detect bacteria in food samples is critical to ensure food safety and minimize the risk of human exposure to potential hazards. A highly sensitive electrochemical sensing platform was developed for the detection of Escherichia coli (E. coli) on fresh leafy vegetables. The sensing platform was assembled based on utilizing genetically engineered bacteriophage T7 encoding with phoA gene as a biorecognition element that can trigger alkaline phosphatase enzyme over-expression upon the target bacterial infection. The alkaline phosphatase over-expression was followed electrochemically using a single-wall carbon nanotube-modified screen-printed electrode. The assembled bacteriophage-based electrochemical sensor is able to provide rapid and accurate detection and quantification of pathogenic E. coli on spinach leaves at a concentration range of 1–104 CFU mL−1 within 1 h after a pre-enrichment. Moreover, the developed biosensor exhibited high specificity toward the E. coli in the presence of other common food bacterial contaminants. The success of this approach provides the potential of the sensor platform to be stretched out to high sensitivity and selectivity detection of different targeted contaminant bacteria in the food samples and reduce the analysis time by coupling between the specifically engineered bacteriophages and the electrochemical methods.