Development of a whole-cell biosensor for the detection of low concentrations of tetracycline

By virtue of genetic engineering technology, we developed a highly sensitive biosensor for tetracycline detection based on the interaction between the tetracycline regulator TetR and tetracycline. In the absence of tetracycline, TetR binds to the tetO sequence, inhibiting the expression of the sfGFP reporter gene. When tetracycline is present, it induces TetR to release from tetO, allowing sfGFP expression. The biosensor was optimized through the selection of transcription factors and reporter genes, and the optimization of spacer lengths. Chassis cells were grown to mid-log phase in a tetracycline-supplemented medium for subsequent fluorescence intensity measurement. The biosensor exhibited a strong linear correlation between fluorescence intensity and tetracycline concentration (I = 37,620.7 × [C(Tc)] + 4048.5, R² = 0.998), demonstrating high sensitivity with a detection limit of 0.0097 mg/L. The response time of the biosensor ranged from 2 to 4 h within the working concentration range, making it suitable for real-time detection. It shows potential for application in actual water sample analysis and as an early warning technology for water pollution risks.