Abstract
Mercury exists naturally and mainly as a man-made pollutant in the environment, where it exerts adverse effects on local ecosystems and living organisms. It is important to develop an appropriate synthetic biological device that recognizes, detects and removes the bioavailable fraction of environmental mercury. Both single-signal and double-signal output mercury biosensors were assembled using a natural mer operon as a template. Selectivity and sensitivity of whole-cell biosensors based on artificial mer operons were determined. Three whole-cell biosensors were highly stable at very high concentrations of mercuric chloride, and could detect bioavailable Hg(II) in the concentration range of 6.25–200 μM HgCl2. A novel Hg(II) bioadsorption coupled with biosensing artificial mer operon was assembled. This would allow Hg(II)-induced Hg(II) binding protein cell surface display and green fluorescence emission to be achieved simultaneously while retaining the linear relationship between fluorescent signal and Hg(II) exposure concentration. The present study provides an innovative way to simultaneously detect, quantify, and remove bioavailable heavy metal ions using an artificially reconstructed heavy metal resistance operon.
Highlights
Mercury is a bioaccumulative and highly toxic heavy metal that is widely dispersed in the environment
The mer operon derived from the E. coli transposon Tn21 is the-best characterized mercury resistance system [19]
It allows different functional elements to be transcribed under the control of its own promoter, followed by the surface display of Hg(II) binding domain (HgBD) for Hg(II) bioadsorption and the expression of eGFP for Hg(II) biosensing at the mean time
Summary
Mercury is a bioaccumulative and highly toxic heavy metal that is widely dispersed in the environment. Environmental mercury exists in three different forms: elemental mercury, inorganic mercury, and organic mercury. Among these forms, organic methyl mercury poses a significant hazard to public health and safety [1]. There are a substantial number of instrumental methods available for the determination and quantification of mercury in different environmental samples, there is a lack of information in speciation studies of mercury in recent years [2]. Measurement of bioavailable Hg(II) has predictive value for the methylation rate of mercury, thereby predicting its biological accumulation in ecosystems [3]. It is imperative to develop appropriate biological devices which detect and remove the bioavailable Hg(II) in the environment
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