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.
Highlights
Foodborne diseases create serious concerns in public health world wide [1,2], considering the acceleration at which foodstuffs move through the production and distribution chain all around the world
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, in five different matrixes of food samples experimentally contaminated and in naturally contaminated foodstuffs
Summary
Foodborne diseases create serious concerns in public health world wide [1,2], considering the acceleration at which foodstuffs move through the production and distribution chain all around the world. It has low sensitivity [10] and requires handling enriched cultures of the pathogen in six sequential steps, using different culture media and biochemical reagents, by a well-trained microbiologist and, at least, one week to isolate suspected colonies, as well as additional period for confirmation and typing in a reference laboratory Such lengthy protocols hamper early detection of foodstuff contaminant pathogens, making urgent the availability of a rapid, cost-effective, sensitive, specific, and easy-to-use system able to detect live bacteria early on in the food chain, especially in those products with a short shelf-life. Both Gram-negative and Gram-negative types of pathogens were detected, under experimental conditions, and in naturally contaminated food samples
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