Assessment of heavy metal bioavailability using Escherichia coli zntAp::lux and copAp::lux-based biosensors

Abstract

To determine the amount of metals detectable by bacteria, two plasmids were constructed in which the metal-inducible zntA and copA promoters from Escherichia coli were fused to a promoterless Vibrio fischeri luxCDABE operon. The luminescence response of E. coli bearing these constructs was studied as a function of the concentration of several heavy metals and was shown to be influenced by cell growth phase. The zntAp::lux fusion is induced mainly by salts of cadmium, lead, mercury and zinc, with significant induction by other metal ions, whereas the specificity of copA induction is restricted to copper and silver. In optimized assay conditions, metals could be detected at threshold concentrations ranging from nanomolar to micromolar, with maximal induction observed after only 60-100 min incubation. The ability of these biosensor strains to distinguish bioavailable quantities of metals in a sample makes them good candidates as useful tools to monitor metal contamination in environmental samples.

The impacts of different long-term fertilization regimes on the bioavailability of arsenic in soil: integrating chemical approach with Escherichia coli arsRp::luc-based biosensor

“…Experiments showed that after a 2-h induction, the biosensor produced an obvious increase of RLU at 0.05 μM As (LOD), which was below the WHO permissible level of 10 μg/L (equivalent to 0.13 μM) in potable water (Nordstrom 2002). In addition, other factors such as the host strain, concentration of host strain, culture medium, and pH could also affect the LOD of a biosensor (Golding et al 2008;Rasmussen et al 1997;Riether et al 2001;Tauriainen et al 1998).…”

Selective detection of gold using genetically engineered bacterial reporters

“…In fact, most of the designed MerR-based biosensors display high sensitivity but low selectivity because the sensor proteins cross-react with a group of related metal ions (Harms, 2007;Hynninen and Virta, 2010;Magrisso et al, 2008). For example, previously constructed Cu biosensors based on CueR, the monovalent metal sensor of the MerR family, detect Cu but also Ag and Au, as the regulator is similarly sensitive to any of these metals (Charrier et al, 2011;Hakkila et al, 2004;Riether et al, 2001;Stoyanov and Brown, 2003). This makes the use of these bioreporters unsuitable for particular applications.…”

Development of a Specific and Sensitive Bacteria Sensor for Detection of Mercury at Picomolar Levels in Environment

“…In addition to genetic constructs, parameters such as cell density in the assay and measurement protocols have been reported to influence the sensitivity of bioluminescence sensor. 5,18) To enhance the sensitivity of the mer-lux biosensor developed, the assay conditions were first optimized. The effect of cell density on the sensitivity of the mer-lux response was shown in Fig.…”