From 2011.igem.org

Revision as of 19:42, 20 September 2011

At a Glance

Pushed for time? Don't worry. Just take a few minutes to read this page which gives a summary of our entire project in a nutshell.

Engineering bacteria to help fight soil erosion

In arid areas of the world soil erosion is a massive problem. It is caused by wind and rain sweeping away the fertile top soil and can eventually result in desertification.

Climate change and unsustainable farming practices are accelerating the rate of desertification to over 31,000 hectares/day. That’s 62, 000 football pitches in a day or half the size of the UK every year.

In ordinary circumstances the roots of well-established plants help to hold down the top soil, protecting it from erosion. In areas that suffer desertification however plants do not get the chance to establish large enough root networks to anchor the soil and themselves before erosion occurs.

This year, Imperial College’s iGEM team have joined the international effort to fight desertification.

We hope to engineer bacteria to accelerate plant root development. The bacteria will be designed to secrete the hormone auxin. Seeds will be coated with the bacteria and then planted in the soil. Once the seeds germinate the bacteria will move towards the roots and be taken in by the plant. Inside the roots the bacteria will release auxin – promoting growth and protecting the soil from erosion.

The modules

Our whole project is sub-divided into three modules. The first, Phyto-Route, involves heterologous expression of the chemoreceptor PA2652 in our chassis, E. coli. PA2652 is responsive to plant root exudates like malate and will allow our engineered bacteria to swim towards plant roots. Once they reach the root, they can be actively taken up by the plant as demonstrated in a recent study on bacterial uptake of GFP expressing E. coli into Arabidopsis roots. The second module, Auxin Xpress, invovles heterologous expression of indole-3-acetic acid (IAA, also known as auxin) in our chassis, via the indole acetamide (IAM) pathway. IAA is known to promote lateral root growth and therefore if it is supplied inside and around the root of a plant, should promote soil stability and prevent erosion. The third and final module, Gene Guard, was designed as a safety measure to minimise the risk associated with release of GMOs into the environment. This involves a toxin/anti-toxin mechanism to prevent horizontal gene transfer of plasmid DNA from our modified bacteria to existing soil bacteria.

Click on the images below to read more about how we designed, modelled, and tested each module.

The engineering cycle

Each module follows the synthetic biology engineering cycle. Since human practice had a huge influence on our project, we included it at the start of the cycle which was followed during the development of our project.

You can read more about the specifications, design, modelling, assembly, and testing of each module following the clickable icons above.

Human Practice, Specs, Design, Modelling, Assembly, Testing

Human Practice

Human practices were an extremely important component of our project and strongly influenced our design. During very early design stages of the project, we consulted social scientists and people involved in NGOs (Greenpeace and the Berkeley Reafforestation Trust) about the viability of our project. In addition, we talked to plant scientists and ecologists to learn more about the specifics and wider impacts of our project. We held two human practices panels that greatly influenced our view of the issues surrounding synthetic biology in general and our project in particular.

We chose our chassis based on concerns surrounding spread of our engineered bacteria into non-targeted environments. In addition, we designed Gene Guard, a novel containment device that prevents the spread of genetic information via horizontal gene transfer. While our project is only at proof-of-concept stage, we wanted to ensure that our approach was as viable as possible. Accordingly, we have created an implementation plan that is based on plans utilised in the agricultural industry for the research and development of new chemicals but also incorporates advice we received from an ecologist and charity members. Finally, we have investigated the legal issues surrounding the release of genetically modified organisms and how they impact our project.

Visit our Human Practice page for an in-depth report on how it influenced our design.

Achievements

Visit our Main Results page for an overview of our main achievements in all modules or visit our Data page for an overview of the BioBricks we constructed and characterised.

Safety and outreach

Reporters and protocols

We created a Dendra2 BioBrick, the first BioBrick on the registry coding for a photoconvertible fluorescent protein. In addition, we re-characterised other fluorescent reporters (have a look on our Reporters page for more details).

Diary, brainstorming & collaboration

Acknowledgment