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Updated: Jun 26, 2025
Quasi-metagenomic Analysis of Salmonella from Food and Environmental Samples
Published on: October 25, 2018
Phage-based magnetic capture method as an aid for real-time recombinase polymerase amplification detection of
Jie Liu1, Shan Shan2, Weihua Lai1
1State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China.
Abstract:
Salmonella is a major cause of foodborne diseases worldwide. Conventional rapid assays for detecting Salmonella in real samples often encounter severe matrix interference or detect a limited number of species of a genus, resulting in inaccurate detection. In this study, we developed a method that combined phage-based magnetic capture with real-time recombinase polymerase amplification (RPA) for the rapid, highly sensitive, and specific detection of Salmonella in milk with an ultra-low detection limit. The Felix O-1 phage-conjugated magnetic beads (O-1 pMBs) synthesized in this method showed excellent capture ability for Salmonella spp. and ideal specificity for non-Salmonella strains. After O-1 pMBs-based magnetic separation, the limit of detection of the real-time RPA assay was 50 cfu/mL in milk samples, which was significantly increased by a magnitude of 3 to 4 orders. The method exhibited a high sensitivity (compatibility) of 100% (14/14) for all tested Salmonella serotype strains and an ideal specificity (exclusivity) of 100% (7/7) for the tested non-Salmonella strains. The entire detection process, including Salmonella capture, DNA extraction, and real-time RPA detection, was completed within 1.5 h. Furthermore, milk samples spiked with 10 cfu/25 mL of Salmonella were detected positive after being cultured in buffered peptone water for only 3 h. Therefore, the proposed method could be an alternative for the rapid and accurate detection of Salmonella.
Insights
This study presents a rapid, sensitive method for detecting Salmonella in milk using phage-based magnetic capture and real-time recombinase polymerase amplification (RPA). The innovative technique achieves ultra-low detection limits within 1.5 hours, improving food safety diagnostics.
Area of Science:
- Food Microbiology
- Molecular Diagnostics
- Biotechnology
Background:
- Salmonella causes widespread foodborne illness globally.
- Existing detection methods face challenges with matrix interference and limited specificity.
- Accurate and rapid Salmonella detection is crucial for public health and food safety.
Purpose of the Study:
- To develop a novel, highly sensitive, and specific method for Salmonella detection in milk.
- To combine phage-based magnetic capture with real-time recombinase polymerase amplification (RPA) for enhanced detection.
- To achieve an ultra-low detection limit and rapid turnaround time for Salmonella analysis.
Main Methods:
- Synthesis of Felix O-1 phage-conjugated magnetic beads (O-1 pMBs) for Salmonella capture.
- Magnetic separation of Salmonella using O-1 pMBs from milk samples.
- Real-time recombinase polymerase amplification (RPA) for sensitive DNA detection.
Main Results:
- The developed method achieved a detection limit of 50 cfu/mL in milk, a 3-4 log order improvement.
- Demonstrated 100% sensitivity for all tested Salmonella serotypes and 100% specificity for non-Salmonella strains.
- Complete detection process, including capture and analysis, was finished within 1.5 hours.
Conclusions:
- The phage-magnetic capture combined with real-time RPA offers a rapid, sensitive, and specific alternative for Salmonella detection in milk.
- This method overcomes limitations of conventional assays, reducing matrix interference and improving accuracy.
- The ultra-low detection limit and short assay time have significant implications for food safety monitoring and outbreak investigations.
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