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 Current Study
The study utilized a genetically modified HEK293 cell line expressing human Toll-like receptor 5 (TLR5) to develop a biosensor for the detection of viable Salmonella. HEK-Blue-hTLR5 cells were cultured in a 96-well tissue culture plate using 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, followed by dilution in phosphate-buffered saline (PBS) to achieve the desired concentrations.
To assess the biosensor's performance, various concentrations of viable Salmonella were added to the HEK-hTLR5 cell cultures. Control experiments included heat-killed Salmonella to evaluate the specificity of the sensor. After a 4 to 6-hour incubation period, supernatants were collected and mixed with Quanti Blue Solution, which detects secreted embryonic alkaline phosphatase (SEAP) activity as a measure of TLR5 activation.
Absorbance was measured at 620 nm using a microplate spectrophotometer to quantify the response. For comparative analysis, traditional microbiological methods were employed, including pre-enrichment in buffered peptone water, selective enrichment in Rappaport-Vassiliadis broth, and plating on XLD agar for colony enumeration.
The results from the biosensor were statistically analyzed using GraphPad Prism software, employing unpaired t-tests and ANOVA with Tukey’s multiple comparison test to determine significance across different experimental groups. This comprehensive approach allowed for a robust evaluation of the HEK-hTLR5 biosensor's efficacy in detecting Salmonella in food samples.
Results and Discussion
The HEK-hTLR5 biosensor effectively detected viable Salmonella in food samples within a significantly reduced timeframe compared to conventional methods. The absorbance readings correlated well with the concentration of viable bacteria, indicating that the biosensor could accurately quantify bacterial presence. The study highlighted the advantages of using SEAP as a reporter gene, as it allows for non-invasive monitoring of cell activity without disrupting the cell monolayers. This feature is particularly beneficial for kinetic studies and real-time monitoring of bacterial interactions.
Furthermore, the biosensor exhibited high specificity for Salmonella, distinguishing between viable and non-viable cells. This capability is crucial for food safety assessments, as non-viable pathogens do not pose a risk to consumers. The incorporation of mammalian cells in biosensor technology represents a significant advancement in the field, as it allows for a more biologically relevant response to pathogens. The study also discussed the potential for integrating this biosensor into portable devices for on-site testing, which could enhance food safety monitoring in various settings, including food processing facilities and retail environments.
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.
Future work may focus on further optimizing the biosensor for a broader range of pathogens and exploring its application in real-world food safety scenarios. The study contributes to the growing body of knowledge in biosensor technology and its application in public health, paving the way for improved food safety measures and consumer protection.
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