Welcome to the 2009 Bacterial Relay Race

In our project we aim to create a cell-to-cell communication system that allows the propagation of a multi-task message with the capability of being reset. To achieve this, the system will include a reengineered conjugation system, a time-delay genetic circuit and a self-destructive plasmid. This system could be the basis for creating a long distance biosensor and/or be applied in reducing antibiotic resistance of bacteria. Furthermore, we have done a parallel research on the different perceptions of iGEM participants and supervisors on ethical issues in synthetic biology. We focused on the consequences of the ultimate conditions of the top-down and bottom-up approaches as applied in biology. We thank everyone who participated in our survey on these ethical issues in synthetic biology.

The Project - Bacterial Relay Race

Project description

Our project is the Bacterial Relay Race. As our team logo and the animation below show, we want to build an improved cell to cell communication system. We choose this subject since most applications or tasks we set to our synthetic biological systems are generally completed by a population of cells, not a single cell. Gaining new insights into cell to cell communication and designing manageable cell to cell communication systems will provide us with a wide range of new possibilities. Manageable cell to cell communication systems could have applications in different fields like therapeutic applications or fermentation technology applications. We are attempting to construct an E.coli strain which is capable of passing a GFP signal through conjugation to other E.coli cells only once, with communication appearing population wide. Our work builds on projects of previous iGEM teams from Berkeley UC and Peking University.

Our project is made up of three modules:

1) Conjugation

Our cell to cell communication system is based on bacterial conjugation. We use this to pass a message, initially GFP, along to other bacteria in the culture.

2) Self Destructive Plasmid (SDP)

In order for our signal to be reset the signal plasmid must be able to self-destruct. The Self Destructive Plasmid (SDP) is degigned to test this functionality. It contains a GFP message, inducible endonuclease gene, and restriction site of this endonuclease. The plasmid is able to degrade itself after receiving the destructing signal.

3) Delay device

It is important that there is a time delay between the time that the signal plasmid is received and its destruction. This gives the cell time to pass the signal plasmid to other cells. If the signal plasmid is degraded too fast after it is received, our relay race would end before reaching the finish line. We therefore constructed a device which is capable of delaying the expression of the endonuclease.

Some potential applications for this project are

1. Grasping of bacterial communication - the communication between bacteria using DNA can advance through bacterial networks, and in this sense our project would allow to send multiple messages in a single DNA, thereby to better understand those bacterial communication networks.
2. Understanding of bacterial antibiotic resistance - these days, bacterial infections are often treated with antibiotics. Unfortunately, bacteria have the tendancy to pass antibiotic resistance to other bacteria through the process of [http://en.wikipedia.org/wiki/Bacterial_conjugation conjugation], thus making the antibiotics useless. Using our project, it might be possible for future researchers to better understand the mechanism by which antibiotic resistance passes among bacterial colonies, and perhaps even inhibit it
3. To test one condition and return to the original state without killing the cell or changing any of its previous genetic and physiological characteristics
4. To generate a pulse in the expression of a certain gene
5. To control the amplitude of the pulse created by the plasmid

The Team

This is the second year, TUDelft participates in the iGEM competition. The group consists of 6 students, 3 instructors and a lot of advisors from TUDelft willing to help out and think with us when it is necessary. An overview of the people involved and our competences can be found on the team page.