Research progress of cadmium whole-cell biosensors
Cadmium whole-cell biosensor(Cd-WCB),which contains a modular genetic circuit assembled by microbial regulation elements,can detect cadmium bioavailability in a simple,low-cost and high-through way.This study outlined the non-specific Cd-WCBs based on transcription factors and enzyme biosensors,and specific Cd-WCBs based on transcription factors and fluorescence resonance energy transfer.The optimization strategies of Cd-WCBs were summarized in this study,including directed mutagenesis and directed evolution of recognition proteins,optimization of genetic circuits with feedback loops,and modification of metalloregulatory system in chassis cells.Cd-WCBs have been applied for the assessment of cadmium bioavailability in different environmental samples,but the viability and detection performance in the actual environment need to be further improved.In future,chassis cells are suggested to be developed and modified to enhance the environmental adaptability of Cd-WCBs,and multiple synthetic biologic methods can be combined to improve the sensitivity and specificity of Cd-WCBs.