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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 IAA expression depends on how the compound is administered to the plant.

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

We will study the effects of chemoreceptor expression level on the chemoattractant detection concentration, thereby determining the appropriate chemoreceptor promoter strength necessary for different plants that secrete different levels of exudates.

3. Improve the MATLAB model for bacterial 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 diverse laboratory conditions. Moreover, in order to make our model more realistic, we will consider death and division of bacteria in future modelling.

3. Perform quantitative analysis

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 also be implemented into chemotaxis modelling of bacterial populations.

2. Model the bacterial uptake by plant root

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

3. 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.