In a recent article published in the journal Biosensors, researchers presented a comprehensive study on the development and application of a cell-based biosensor for the rapid detection of Salmonella, a significant foodborne pathogen. This study aims to address these challenges by utilizing a HEK-hTLR5 reporter cell line, which can provide quicker and more accurate detection of viable pathogens in food samples.
Study: Salmonella Detection in Food Using a HEK-hTLR5 Reporter Cell-Based Sensor. Image Credit: Babul Hosen/Shutterstock.com
Background
Salmonella is a leading cause of foodborne illness worldwide, with significant public health implications. Conventional detection methods typically involve multiple steps, including pre-enrichment, selective enrichment, and biochemical testing, which can extend the time required for results to five to seven days. These methods often lack the specificity needed to differentiate between viable and non-viable cells, which is crucial for assessing food safety.
Recent advancements in biosensor technology, particularly those incorporating mammalian cells, have shown promise in providing rapid and reliable detection of pathogens. The HEK-hTLR5 cell line, which expresses Toll-like receptor 5 (TLR5), is particularly suited for this purpose as it can respond to bacterial flagellin, a component of Salmonella, thereby enabling the detection of live bacteria.
The Study
The study developed a biosensor for detecting viable Salmonella using a genetically modified HEK293 cell line expressing human Toll-like receptor 5 (TLR5). HEK-Blue-hTLR5 cells were cultured in a 96-well tissue culture plate with Dulbecco's Modified Eagle Medium (DMEM), supplemented with 10 % fetal bovine serum (FBS) and antibiotics. Salmonella strains were grown overnight in Luria-Bertani (LB) broth at 37 °C and diluted in phosphate-buffered saline (PBS) to achieve the desired concentrations.
To evaluate the biosensor’s performance, varying concentrations of viable Salmonella were introduced to the HEK-hTLR5 cell cultures. Control experiments included heat-killed Salmonella to assess the sensor’s specificity. After a 4 to 6-hour incubation, the supernatants were collected and mixed with Quanti Blue Solution to detect secreted embryonic alkaline phosphatase (SEAP), an indicator of TLR5 activation.
Absorbance at 620 nm was measured using a microplate spectrophotometer to quantify the response. Traditional microbiological methods were used for comparison, including pre-enrichment in buffered peptone water, selective enrichment in Rappaport-Vassiliadis broth, and plating on XLD agar for colony enumeration.
The data was then statistically analyzed using GraphPad Prism software, applying unpaired t-tests and ANOVA with Tukey’s multiple comparison test to assess significance across experimental groups. This comprehensive approach provided a robust evaluation of the HEK-hTLR5 biosensor’s efficacy in detecting Salmonella in food samples.
Results and Discussion
The HEK-hTLR5 biosensor was able to effectively detect viable Salmonella in food samples within a significantly shorter timeframe compared to conventional microbiological methods. The absorbance readings demonstrated a strong correlation with the concentration of viable bacteria, confirming the biosensor’s ability to accurately quantify bacterial presence. The use of SEAP as a reporter gene proved advantageous, allowing for non-invasive monitoring of cell activity without disrupting cell monolayers. This feature is particularly useful for kinetic studies and real-time monitoring of bacterial interactions.
Moreover, the biosensor exhibited high specificity for Salmonella, successfully distinguishing between viable and non-viable cells. This is a critical feature for food safety assessments, as non-viable pathogens pose no risk to consumers. The integration of mammalian cells in biosensor technology marks a significant advancement, providing a more biologically relevant response to pathogen detection compared to traditional methods.
The study also explored the potential for adapting this biosensor into portable devices for on-site testing, which could greatly enhance food safety monitoring in environments such as food processing facilities and retail outlets. This integration would enable rapid and reliable detection of pathogens, improving the efficiency of food safety assessments and reducing the risk of contamination in the supply chain.
Conclusion
In conclusion, the study successfully developed a HEK-hTLR5 cell-based biosensor for the rapid detection of Salmonella, demonstrating its potential as a reliable tool for food safety monitoring. The biosensor's ability to differentiate between viable and non-viable cells, coupled with its rapid response time, positions it as a valuable alternative to traditional detection methods. The research highlights the importance of integrating advanced biosensor technologies into food safety practices to enhance the efficiency and accuracy of pathogen detection.
Journal Reference
Eser E., Felton V.A., et al. (2024). Salmonella Detection in Food Using a HEK-hTLR5 Reporter Cell-Based Sensor. Biosensors 14, 444. DOI: 10.3390/bios14090444, https://www.mdpi.com/2079-6374/14/9/444
Article Revisions
- Sep 24 2024 - Revised sentence structure, word choice, punctuation, and clarity to improve readability and coherence.