Team:BS United China/Design

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Design

Abstract

The food contamination is a serious threat for people’s health, especially the food that’s contaminated but looks good on the outside. Due to experiment on the fish and meat bought from the market, the intensity of P. aeruginosa, the main group of pathogenic bacteria is sometimes high enough to cause uneasiness and other body issues. So, a product with the ability to detect the intensity of P. aeruginosa and to inhibit it is needed. That’s our product, AHL scout and AHL terminator.

Design of the AHL scout

We engineered the E. coli cell to link the LuxR gene with the mCherry Gene to illustrate the concentration of AHL molecules. We engineered it by using the solution of plasmid added into the solution of the cells in receptive state. The choice of the gene is due to the role of AHL as the signal molecule in the quorum sensoring. So the concentration of it could represent the degree of qurom sensoring. When the IPTG first inhibits the Lac promoter, the LuxR would be activated and activate the AHL reaction site. When the AHL is molecule is detected by the LuxR molecule, then the mCherry gene would be activated. After transcription and translation, the fluorescence protein would be produced and would produce fluorescence protein. In this case, the light intensity represent the concentration of the AHL molecule and thus the contamination status.

Design of the AHL terminator

We engineered the E. coli to use PVDQ protein to inhibit the bacteria to reduce the contamination of the food. To achieve this, we added the bio-bricks to the E. coli to connect the PVDQ gene to the activation of QS promoter. When the LuxR is activated, the PVDQ gene would be activated and transcript to mRNA and translate to PVDQ protein. PVDQ would reduce the concentration of AHL and thus prevent the biofilm from forming and reduce the contamination. In order to make the process more obvious, the start of the PVDQ gene is also connected with the green fluorence gene and would produce GFP with PVDQ. Therefore, the brightness of the green flourence can be seen as the signal of the inhibition of the bacteria. The terminator should be in the same bacteria as the AHL scout, However, in order to make the detection of the AHL scout more obvious and more usable in situations of inspection, the terminator and the scout are separated.

Choice of the PVDQ proteins

The existence of the inhibitor, whatever it is, may be a reason of concern for those who wanted to use the product. Therefore, the inhibitor need to be able to degrade in the body of the human. Hence, the choice of the inhibitor is a kind of protein since the proteins are easy to be degraded. The PVDQ proteins, after being degraded in the solution of 3% hydrochloride and 17% acetic acid at 37 degrees Celsius for 30 minutes, are all completely decomposed. Therefore, the PVDQ protein could be decomposed and is a choice for the inhibitor.