Our FerriTALE

The Problem

Enterohemorrhagic E. coli (EHEC) causes sickness in over a quarter of a million people each year, costing billions of dollars worldwide. These bacteria live peacefully in the gut of cattle, but if these bacteria are present in water, vegetables or meat that is consumed by people, we can become extraordinarily ill. Within the cattle population only a small portion of animals, about 5%, produce the vast majority, about 95%, of the EHEC found in cattle and the surrounding environment. These cattle with high bacterial loads are known as "super-shedders" as they contain anywhere from 100 to 10000 times as many colony forming units of these bacteria. Such high amounts of EHEC being excreted into the cattle surroundings produce prime opportunities for EHEC to contaminate ground water, vegetables and surrounding cattle hyde in the same holding pen. The contaminated hyde of the cattle could then contaminate the meat causing illnesses to consumers. If the super-shedders cattle are detected prior to entering the processing plants, the contamination of water, vegetables and meat could be reduced.

Our Goal: to design and build a synthetic biology system capable of identifying EHEC super-shedding cows.

The Solution

Before embarking on our project, we asked ourselves how does the industry views these challenges. This led to our systems informed design by initiating discussions with industry that we continued throughout the development of our project. We believe developing a product should involve consumer input at all steps of development. This core belief in informed design has led us to build a system that can achieve scientific rigor and meet the needs the industry has indicated to us for a biosensor. To read more about our user-focused, informed design approach to human practices click here.

To detect EHEC bacteria in a sample we developed a unique detection strategy combining tools available in iGEM as well as the literature. We designed DNA binding proteins available in iGEM that allow us to capture sequences only found in the pathogenic E. coli coupled with a chemically modified protein nanoparticle that acts as a rapid catalyst to create a readable colour change in a matter of seconds. To aid in tuning our system we created a mathematical model to predict the amount of DNA binding proteins needed for varying levels of sensitivity, alongside two spatial models to demonstrating how our system works. Finally, we designed a physical prototype of our system and were able to obtain some preliminary data as to its functionality. More on the scientific details of our project can be found here.

As well as focusing solely on our project, we felt the need to give back to the iGEM community as a whole. Early in the planning stages of our project our team was looking into past projects and found a staggering number of biosensors. By joining forces with Paris-Bettencourt's iGEM team we have created the first database of sensors created by iGEM teams, SensiGEM. This tool will aid in streamlining the design process for future teams doing projects with the theme of a biosensor. To learn more about our collaboration click here.