Simultaneous detection of bioavailable arsenic and cadmium in contaminated soils using dual-sensing bioreporters

Abstract

Whole-cell bioreporters (WCBs) have attracted increasing attention during the last few decades because they allow fast determination of bioavailable heavy metals in contaminated sites. Various WCBs to monitor specific heavy metals such as arsenic and cadmium in diverse environmental systems are available. However, currently, no study on simultaneous analysis of arsenic and cadmium has been reported, even though soils are contaminated by diverse heavy metals and metalloids. We demonstrated herein the development of dual-sensing WCBs to simultaneously quantify bioavailable arsenic and cadmium in contaminated sites by employing the promoter regions of the ars and znt operons as separate metal-sensing domains, and egfp and mcherry as reporter genes. The dual-sensing WCBs were generated by inserting two sets of genes into E. coli DH5α. The capability of WCBs was successfully proved to simultaneously quantify bioavailable arsenic and cadmium in amended Landwirtschaftliche Untersuchungs und Forschungsanstalt (LUFA) soils, and then, it was applied to contaminated field soils collected from a smelter area in Korea. As a result, it was noticed that the bioavailable portion of cadmium was higher than that of arsenic while the absolute amount of bioavailable arsenic and cadmium level was opposite. Since both cadmium and arsenic were assessed from the same E. coli cells, the data obtained by using dual-sensing WCBs would be more efficient and convenient than that from comparative WCB assay. In spite of advantageous aspects, to our knowledge, this is the first report on a dual-sensing WCB for rapid and concurrent quantification of bioavailable arsenic and cadmium in contaminated soils.

Engineering a palette of eukaryotic chromoproteins for bacterial synthetic biology

“…Current methods for detecting environmental, agricultural and food contaminants, landmines and biowarfare agents, and medically-relevant targets can be improved by synthetic biology [ 10 ]. For example, bacteriophage have been engineered to cause bioluminescence of pathogenic bacteria in food, and bacteria have been engineered to fluoresce upon detection of spoiled meat gas [ 11 ], trinitrotoluene (TNT) products [ 12 ] or arsenic [ 13 ]. Adaptation of these biosensors to non-fluorescent detection for use in supermarkets or the field beckons, but it is unclear which CP genes might be suitable or how best to assay them quantitatively.…”

Sensitive and Specific Whole-Cell Biosensor for Arsenic Detection

“…So overall, it showed a dramatic difference in the fluorescence in response to arsenite and other metals. Many arsenite WCBs have specificity issue (39,43). Generally, the specificity may be improved by protein engineering to modify the interaction between the regulator and the inducer metal ions.…”

Handbook of Cell Biosensors

“…Dual sensing WCBs are another very useful monitoring possibility as it can detect two different metals with different sensitivity. A dual sensing WCB based on E. coli has been designed to detect bioavailable As(III) or As(V) and Cd(II) in polluted soil samples (Yoon et al 2016a). It carries two different genetic constructs: P ars :: mCherry (a monomeric red fluorescent protein) and P znt ::eGFP (enhanced GFP version) or the cross-combination fusions P ars ::eGFP and P znt ::mCherry.…”