Plasmon-assisted fast colorimetric detection of bacterial nucleases in food samples

Abstract We have developed a rapid, inexpensive, colorimetric and easy to use method able to detect living bacterial pathogens of zoonotic and foodborne interest. The method is based on detection of bacterial nucleases which cut selectively oligonucleotide probes that are designed in a way to induce aggregation of oligonucleotide stabilised gold-nanoparticles. We present the standardization of our method to detect nucleases secreted by Gram-positive (Staphylococcus aureus) and Gram-negative (Salmonella spp.) pathogens, not only in five different matrixes of food samples experimentally contaminated but also in naturally contaminated foodstuffs. Our method has shown sensitivity/specificity, detecting nucleases in less than two hours in supernatants from bacterial cell culture (1 CFU/mL) incubated for 15 h. The nucleases are detected by naked-eye inspection, and using minimal laboratory equipment. From a broader perspective, besides applications in foodstuff safety, we envision a potential use of our method to detect other bacterial and viral pathogens in the environment, and in veterinary and human health.