Highly Sensitive Whole-Cell Biosensor for Cadmium Detection Based on a Negative Feedback Circuit

Frontiers in Bioengineering and Biotechnology

Xiaoqiang Jia¹  Guangbao Zhang²  Shuting Hu² 

[1] Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, China;Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China;Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China;

关键词: cadmium detection;    negative feedback amplifier;    sensitivity;    specificity;    whole-cell biosensor;   

DOI  :  10.3389/fbioe.2021.799781

来源: DOAJ

【 摘 要 】

Although many whole-cell biosensors (WCBs) for the detection of Cd2+ have been developed over the years, most lack sensitivity and specificity. In this paper, we developed a Cd2+ WCB with a negative feedback amplifier in P. putida KT2440. Based on the slope of the linear detection curve as a measure of sensitivity, WCB with negative feedback amplifier greatly increased the output signal of the reporter mCherry, resulting in 33% greater sensitivity than in an equivalent WCB without the negative feedback circuit. Moreover, WCB with negative feedback amplifier exhibited increased Cd2+ tolerance and a lower detection limit of 0.1 nM, a remarkable 400-fold improvement compared to the WCB without the negative feedback circuit, which is significantly below the World Health Organization standard of 27 nM (0.003 mg/L) for cadmium in drinking water. Due to the superior amplification of the output signal, WCB with negative feedback amplifier can provide a detectable signal in a much shorter time, and a fast response is highly preferable for real field applications. In addition, the WCB with negative feedback amplifier showed an unusually high specificity for Cd2+ compared to other metal ions, giving signals with other metals that were between 17.6 and 41.4 times weaker than with Cd2+. In summary, the negative feedback amplifier WCB designed in this work meets the requirements of Cd2+ detection with very high sensitivity and specificity, which also demonstrates that genetic negative feedback amplifiers are excellent tools for improving the performance of WCBs.

【 授权许可】

Unknown