Fang T, Shen J, Xue J, Jiang Y, Guo D, Yang J, Kong X, Xu X, Wang X. Sensitive and Rapid Detection of Escherichia coli O157:H7 From Beef Samples Based on Recombinase Aided Amplification Assisted CRISPR/Cas12a System.
J AOAC Int 2022;
106:156-164. [PMID:
36005831 DOI:
10.1093/jaoacint/qsac101]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 08/16/2022] [Accepted: 08/16/2022] [Indexed: 12/27/2022]
Abstract
BACKGROUND
Escherichia coli O157:H7, being the cause of hemorrhagic colitis in humans, is recognized as one of the most dangerous and widespread foodborne pathogens. A highly specific, sensitive, and rapid E. coli O157:H7 detection method needs to be developed since the traditional detection methods are complex, costly, and time-consuming.
OBJECTIVE
In this study, a recombinase aided amplification (RAA) assisted CRISPR/Cas12a (RAA-CRISPR/Cas12a) fluorescence platform for specific, sensitive, and rapid nucleic acid detection of E. coli O157:H7 was introduced.
METHODS
First, the feasibility (components of CRISPR/Cas12a system) of the developed method was evaluated. Then a total of 34 bacterial strains were used for the specificity test, and gradient dilutions of extracted DNA and bacterial solutions of E. coli O157:H7 were prepared for the sensitivity test. Third, a real-time PCR assay for detection of the specific wzy gene of E. coli O157:H7 (FDA's Bacteriological Analytical Manual) was used for sensitivity comparison. Finally, analysis of RAA-CRISPR/Cas12a detection in spiked and 93 real ground beef samples was carried out.
RESULTS
The developed RAA-CRISPR/Cas12a method showed high specificity, and the detection could be completed within 30 min (after 4 h enrichment in spiked ground beef samples). The limit of detection (LOD) of bacterial concentrations and genomic DNA was 5.4 × 102 CFU/mL and 7.5 × 10-4 ng/μL, respectively, which exhibited higher sensitivity than the RAA-gel electrophoresis and RT-PCR methods. Furthermore, it was shown that E. coli O157:H7 in ground beef samples could be positively detected after 4 h enrichment when the initial bacterial inoculum was 9.0 CFU/25 g. The detection results of the RAA-CRISPR/Cas12a method were 100% consistent with those of the RT-PCR and traditional culture-based methods while screening the E. coli O157:H7 from 93 local collected ground beef samples.
CONCLUSIONS
The developed RAA-CRISPR/Cas12a method showed high specificity, high sensitivity, and rapid positive detection of E. coli O157:H7 from ground beef samples.
HIGHLIGHTS
The RAA-CRISPR/Cas12a system proposed in this study provided an alternative molecular tool for quick, specific, sensitive, and accurate detection of E. coli O157:H7 in foods.
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