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From 2011.igem.org

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Module 1: Phyto-Route

Chemotaxis is the movement of bacteria based on attraction or repulsion of chemicals. Roots secrete a variety of compounds that E. coli are not attracted to naturally. Accordingly, we engineered a chemoreceptor into our chassis that can sense malate, a common root exudate, so that it can swim towards the root. Additionally, E. coli are actively taken up by plant roots, which will allow targeted IAA delivery into roots by our system.

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Future Work

To carry on the work on the Phyto-Route module, there are a number of steps we would take in the immediate future and others that form part of our long term plan.

Short-term plans

1. Repeat experiment of bacterial uptake into plants.

Repeat the uptake experiment in non-sterile conditions in soil in order to assess if uptake of bacteria is likely to happen in nature. This is especially important as the fine tuning of auxin expression depends on how the compound is administered to the plant.

2. Study the relations between chemoreceptor concentration and the threshold chemoattractant detection concentration in single chemotaxis pathway

We will study the effects of chemoreceptor expression level on the chemoattractant detection concentration, therefore determine appropriate chemoreceptor promoter for different plants

3. Improve the MATLAB model for bacteria chemotaxis under laboratory conditions

We will improve this model by adding more input parameters (i.e. the distance between the chemoattractant source and the bacteria), and therefore make it applicable to more different laboratory conditions. Moreover, in order to make our model more realistic, we will consider death and division of bacteria in our future modelling.

3. Perform quantitative analysis

Given more time, we would like to perform a functioning capillary assay to ascertain the relationship between malate concentration and chemotaxis response.

4. Continue studying behavior

In order to obtain more reliable data, we would like to repeat the behavioral analysis on the tumbling frequencies of our constructs.

Long-term plans

1. Improve the model of malate distribution and the chemotaxis bacterial population in soil

We will improve the malate distribution model by considering more complexities of the soil, this study will be also implemented into chemotaxis modelling of bacterial populations.

2. Model the bacteria uptake of plant root

We will develop mathematical model for bacteria uptake by plant root, and the movement and distribution of bacteria inside the root will be also studied

2. Test whether the bacteria will chemotax towards the root

In order to test whether the chemotactic bacteria will swim to the root we wish to perform an experiment. We think that we could take advantage of the root uptake experiment to see whether there is a difference in root uptake between a bacteria with PA2652 and without.

3. Testing and implementation in the field.