Improving Electrochemical Aptasensor Sensitivity for Bacillus cereus Spore Detection in Food Safety Applications

Rapid detection of Bacillus cereus spores is critical for preventing food contamination and spoilage. Many existing methods detect B. cereus cells instead of spores, and cannot be applied directly in foods. Here, combination of aptamers that bind different moieties at the surface of B. cereus spore with rapid electrochemical detection is presented. When different DNA aptamers were immobilized on screen printed gold electrode, they showed higher binding capacity for B. cereus spores than individual aptamers suggesting a synergic effect. The biosensor exhibited a wide dynamic range (102 - 107 CFU/mL) of low limits of detection (∼1 CFU/mL) using just 15 μL of sample. Validation in spiked salad, using direct spore sensing in rinse water and comparing it to the culturing method, confirmed its sensitivity and specificity. This aptamer-combined approach achieving the rapid (15 min) and single-step detection may also be suitable for detecting other foodborne pathogens.