Team:Peking/Project/Application/KitOperation

From 2010.igem.org

Here is a general view of how our heavy metal decontamination biokit functions. Our biokit consists of two parts: the bioreporter and the bioabsorbent. We can firstly determine the heavy metal pollution level by the bioreporter, and then clean the contaminated water exploiting the bioabsorbent.

When heavy metal emerges, a tri-node response will be switched on in our biosensor (Fig.1). Different strains with parameter variations between the nodes will have different response threshold to heavy metal ions, such as mercury.

Fig 1. Structure of Tri-node response system. According to the results of modeling, we designed the specific genetic circuit to realize the linear response function. Node A is a generator of MerR. For Node B, the gene is the activator which can activate the psid promoter. Node C is GFP whose expression was driven by Psid (activated by activator) and PmerT (activated by MerR).

Since the transfer function of bioreporter response represents linear now. The working range of the bioreporter will be expanded, and the error rating will be reduced. This type of bioreporter will be excellent for in lab accurate measurement or heavy metal pollution assessment.

Fig 2. Our bioreporter with tri-node response system will possess a linear transfer function (right) rather than the natural hill function (left).

Before wiki freezing, data collecting of the final result (linear transfer function transformed from hill function) are still under progressing. Primary result demonstrates that it works as expected, which we will show at Jamboree.

To determine the pollution level in field, we developed an assay easy to understand and accessible to the general public, called traffic light bioassay. By using bacteria strains with different sensitivity threshold to mercury, the heavy metal concentration can be easily determined by the number of reporter strains reacting to a sample, which is representative to different heavy metal concentration range (Fig.3).

Fig 3. The schematic sketch of how the biosensor functions.