CRISPR Cas12a-based "sweet" biosensor coupled with personal glucose meter readout for the point-of-care testing of Salmonella.

Abstract

Salmonella is a pathogen that comes from different animal-originated foods and poses a significant threat to human health. The present detection methods for Salmonella are time-consuming and labor-intensive and requires skilled workers and specialized instruments. In this study, the conservative invA was selected as the target gene, and a quantitative detection method for Salmonella with wide availability and user-friendliness was established based on CRISPR Cas12a and a personal glucose meter (PGM). The indirect signal transformation from the original target DNA to the final glucose signal was achieved through RAA, CRISPR Cas12a reaction, enzymic reaction, and glucose signal reading by a PGM (accu-chek type from Roche). This PGMs-CRISPR assay showed a detection sensitivity of Salmonella as low as 5 colony-forming units (CFU)/reaction in either pure culture or artificially contaminated food samples and exhibited specificity between Salmonella isolates and non-Salmonella isolates. Furthermore, quantitative detection of Salmonella in spiked milk samples was also achieved within the range from 1 to 1 × 103 CFU/reaction. Subsequently, the correlation and consistency between the PGMs-CRISPR assay and quantitative polymerase chain reaction (qPCR) in detection of Salmonella in spiked milk samples were achieved. Therefore, a highly sensitive, portable, quantitative, and user-friendly detection method based on CRISPR Cas12a and PGMs was developed in this study for Salmonella detection and identification. PRACTICAL APPLICATION: A sensitive, rapid, user-friendly, and quantitative detection method based on CRISPR Cas12a for Salmonella in food has been developed in this study, which is of great significance to food safety supervision and management.