Rapid and highly sensitive detection of Salmonella using specific aptamers and nucleic acid enrichment technology

Salmonella is a significant pathogen that is responsible for foodborne diseases, and the rapid detection of this pathogen is crucial for ensuring food safety. Traditional detection methods are often time-consuming due to the requirement of bacterial enrichment. To address these challenges, this study developed a novel Salmonella enrichment technique utilizing carboxylated magnetic beads and ultrafiltration membranes, and designed and synthesized a specific nucleic acid aptamer targeting the invA gene of Salmonella. By integrating nucleic acid enrichment technology with a specific aptamer, we achieved quantitative detection of low-concentration Salmonella using fluorescence spectrometry without the need for conventional enrichment steps. This method demonstrated a detection limit as low as 1 colony-forming units (CFU)/mL, a linear range from 100 CFU/mL to 10³ CFU/mL, and a correlation coefficient of R² = 0.9864. Compared with conventional methods, this approach exhibited 2.4-fold greater sensitivity accompanied by significant signal amplification. In terms of stability, when the concentration of unknown Salmonella was measured via plate counting methods, a value of 5.76 × 10² CFU/ mL was obtained, comparing well with our method, which yielded a concentration of 5.49 × 10² CFU/mL, indicating good performance. Additionally, this method exhibited high specificity, which allowed for the accurate detection of Salmonella even in the presence of multiple interfering bacteria, including Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, and Shigella spp. This novel technique overcomes the limitations of traditional enrichment-based methods, thereby offering an efficient and rapid approach for Salmonella detection in food, with broad potential for practical applications.