iGEM Bielefeld 2015

Heavy Metals


Adjusting the detection limit
Figure 1: Influence of heavy metals on the growth of E.coli KRX. The tested concentrations were 20 µg/L lead, 60 µg/L mercury, 60 µg/L chromium, 80 µg/L nickel, 40 mg/L copper, which represent ten times the WHO guideline. The influence of arsenic was not tested as E. coli is known to be resistant to arsenic.

We tested our heavy metal biosensors in Escherichia coli as well as in our cell-free protein synthesis.

Prior to the in vivo characterization, we tested whether the heavy metals have a negative effect on the growth of E. coli.

As can be seen from the figure, we observed no significant difference between the growth in the presence of heavy metals and the controls. This first experiment showed us that in vivo characterization of these sensors is possible. Most cultivations for in vivo characterization were performed in the BioLector. Due to the accuracy of this device, we could measure our samples in duplicates. Subsequently, all functional biosensors were tested in vitro.

Click on the test strip for the results of our biosensor tests in E. coli and in our CFPS:


To summarize all

We have characterized heavy metal sensors for arsenic, chromium, copper, lead, mercury and nickel. The results for our nickel characterization indicated that the constructed nickel sensor is not suitable for our test strip. The sensors for lead and chromium showed great potential, as they showed responses to chromium or lead, but require further optimization. Copper, our new heavy metal sensor, worked as expected and was able to detect different copper concentrations. The already well-characterized sensors for arsenic and mercury were tested as well. While the arsenic sensor worked well in vivo, it requires some omptimization for the use in vitro. Mercury showed that a fully optimized sensor works very well in our in vitro system and has the potential to detect even lower concentrations than in vivo.