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 extrordinarily ill. Within the cattle population only a small portion of animals, about 5%, produce the vast major, about 95%, of the EHEC bacteria found in cattle and the surrounding evironment. These cattle These high bacterial load cows 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 cattles surroundings produce prime opportunities for EHEC to contaminate ground water and vegetables. Additionally, such high amounts of EHEC pose a large concern to the beef industry when slaughtering the animals. If the super-shedders cattle could be identified before they enter processing plants, the contamination of water, vegatbles and meat could be reduced.

This is our projects goal: to design and build a biologically-based system capable of detecting these 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 that research aiming to solve a problem should have input from all involved parties at all times. 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. More on our user-focused, informed design approach to human practices can be found here.

To detect EHEC bacteria in a sample we have developed a unique detection strategy that combines tools from past iGEM teams and matured technologies in a new system called a FerriTALE. We have designed DNA binding proteins 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, as well as giving information to the general public about the awesome projects iGEM teams worldwide have been involved in. More on our collaboration can be found here.