# Sensing Cellular Damages Induced by Food Safety Hazards Using Bacterial Stress-Responsive Biosensors

## TL;DR

Researchers developed bacterial biosensors to detect specific types of cellular damage caused by food safety hazards, offering a sensitive and cost-effective alternative to traditional methods.

## Contribution

A panel of Escherichia coli whole-cell biosensors was developed to distinguish different types of cellular damage with high specificity and sensitivity.

## Key findings

- An optimized RecA-LexA-based DNA damage biosensor achieved a 35.5% reduction in baseline signal and 36.6-fold fluorescence induction.
- Promoters Pfpr, PkatG, PgrpE, and PfabA were identified for constructing biosensors targeting oxidative, proteotoxic, and membrane stress.
- The DNA damage biosensor detected norfloxacin with an LOD of 1.3 ng/mL in solution and 3.0 ng/mL in milk, comparable to HPLC.

## Abstract

Food safety hazards induce diverse cellular damages including DNA damage, oxidative stress, proteotoxic stress, and membrane disruption, ultimately contributing to various human diseases. Conventional toxicity assays, while effective, are often resource-intensive and lack the capacity to distinguish among these different damage types, thereby limiting insight into toxic responses and the development of effective strategies for targeted risk mitigation. Here, we constructed a panel of Escherichia coli whole-cell biosensors capable of distinguishing distinct categories of cellular damage. Specifically, an optimized RecA-LexA-based DNA damage biosensor that precisely controls the exogenous expression of the transcriptional repressor LexA achieved a 35.5% reduction in baseline signal and a 36.6-fold induction of fluorescence. In parallel, systematic promoter screening identified Pfpr, PkatG, PgrpE, and PfabA as effective modules for constructing oxidative, proteotoxic, and membrane stress biosensors. These biosensors exhibited high specificity and sensitivity, generating dose-dependent responses to model toxicants and enabling discrimination of cellular damage induced by typical hazards such as norfloxacin and ciprofloxacin. Notably, the DNA damage biosensor detected norfloxacin with a limit of detection (LOD) of 1.3 ng/mL in standard solution and 3.0 ng/mL in milk, comparable to that of high-performance liquid chromatography (HPLC). Together, our work not only provides a versatile, cost-effective, and sensitive tool for assessing diverse cellular damages induced by food safety hazards, but also demonstrates potential utility for practical food safety monitoring.