Abstract
It is important to have tools to measure the bioavailability to assess the risks of pollutants because the bioavailability is defined as the portions of pollutants showing the biological effects on living organisms. This study described the construction of tunable Escherichia coli whole-cell bioreporter (WCB) using the promoter region of zinc-inducible operon and its application on contaminated soils. It was verified that this WCB system showed specific and sensitive responses to cadmium rather than zinc in the experimental conditions. It was inferred that Cd(II) associates stronger with ZntR, a regulatory protein of zinc-inducible operon, than other metal ions. Moreover, the expression of reporter genes, egfp and mcherry, were proportional to the concentration of cadmium, thereby being a quantitative sensor to monitor bioavailable cadmium. The capability to determine bioavailable cadmium was verified with Cd(II) amended LUFA soils, and then the applicability on environmental systems was investigated with field soils collected from smelter area in Korea before and after soil-washing. The total amount of cadmium was decreased after soil washing, while the bioavailability was increased. Consequently, it would be valuable to have tools to assess bioavailability and the effectiveness of soil remediation should be evaluated in the aspect of bioavailability as well as removal efficiency.
Highlights
Environmental pollution caused by anthropogenic activities is considered a major threat to human health
We describe here the characterization of E. coli whole-cell bioreporter (WCB) based on zntAp and report the bioavailability of cadmium in contaminated soils
The metal selectivity of WCBs based on zntAp was investigated with As(III), Zn(II), Co(II), Cr (VI), Hg(II), Pb(II), Cu(II), and Cd(II)
Summary
Environmental pollution caused by anthropogenic activities is considered a major threat to human health. Pollutants such as heavy metals that enter into the ecosystem can transfer to living organisms by diverse exposure routes, and pollutant accumulation has been shown to cause toxicity in humans with prolonged direct and indirect exposure [1,2,3]. Pollutants have been monitored by analytical instruments that are expensive and time-consuming to use. These instruments are unable to distinguish bioavailable portions from unavailable pollutants in order to assess the risks of pollutants to living organisms.
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