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From 2013.igem.org

Contents 1 Backgrounds 2 App 3 Methods 4 Results Summary

Backgrounds

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The goal for this app is to make a standardized system for light control without the common problems many of the current ad hoc light projection systems come with: high cost, difficult assembly, and low reproducibility. With mobile device tablets integrating into our everyday lives, we found it fitting to develop a program to take advantage of their pervasiveness and utilize them as synthetic biology instruments.

E. colight was a tablet application designed by our iGEM 2012 team in order to project light onto bacterial cultures. This year, our team wanted to continue our 2012 project by expanding the functionality of our app, calibrate it using existing light-inducible promoter systems, and determine the maximum number of experiments we can perform on a single tablet. By designing experiments with high reproducibility that explores the strengths and limitations of the app, we hope to create the canonical system for optogenetics testing.

In addition to characterizing in depth the use of the app, we also developed new features that can accommodate a broader range of growth vessels, a vibration feature, and utilize the heat output of the processor as an incubator.

App

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E colight has been designed to shine different wavelengths of light on growing bacterial cultures. The app was designed and tested on the Samsung Galaxy Tab 7.7 which has an Super AMOLED display. Each pixel on an Super AMOLED display is made up of three LEDs corresponding to each of the colors in the RGB color format. This format is advantageous for the green light inducible system because the green output of the display is monochromatic in that only the green LEDs are turned on. Furthermore, the RGB LEDs output spectrum are very compatible with published red [1], green [2], and blue [3] light gene inducers. Another advantage of the display allows for a “true black”, which emits no light and minimizes background effects [old - in that no light is emitted which would allow for the lowest level of background] in a light inducible system. Finally, development of our app in the Android operating system allows for the easiest distribution of our app to actual users due to its open source nature, lower relative cost of Android mobile devices, and accessibility of the Google Play Store.

-Close up picture of Super AMOLED screen http://en.wikipedia.org/wiki/AMOLED/

One our primary goals was to make this app flexible and useful for multiple microbial growth formats. The app was designed for experiments that use standard sized petri dishes, 60 mm petri dishes, and 96-well plates for both liquid and solid phase media. Each light-emitting unit can be controlled individually, which allows for multiple experiments to be performed simultaneously. In the case of the 96-well plate, this means each well can be controlled individually, which potentially allows for 96 simultaneous yet different experiments. In addition to these default settings, the diameters of the wells can also be adjusted to the user’s current experimental setup as well as the intensity and wavelength of the light. Samples can be exposed to mixtures of wavelengths through a blinking option which cycles through the RGB colors.

"FIGURE REQUEST:  Light spectral data"

We implemented a vibration setting with the intention of agitating liquid cultures to promote growth. Though this feature is fully functional in the current release, users are advised against extended periods of activation as the hardware cannot sustain high intensity vibration without failure. For this reason, the tablets were placed on orbital shakers to provide the agitation required for rapid growth.

"FIGURE REQUESTS:"

- screenshots

- video demo

Methods

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We have biobricked the previously published red and green light responsive systems and characterized them on our mobile tablet device. The potential applications for a mobile light-inducible expression system are numerous for researchers, iGEM teams, and also in resource-poor settings. Both complex spacial patterning and simple expression gradients are highly useful to synthetic biology community. Spacial control allows the induction of cellular patterns to simulate signalling gradients in tissue development and are useful in lithography and other pattern related technology.

Expanding the development of our light-inducing app will give iGEM researchers the ability to express gene products and initiate circuits simply with light in varying intensities for a range of expression levels. The 96-well format allows for the testing of many different constructs at the same time, greatly increasing the potential experimental throughput.

Our proposal of a a ‘hot-swappable’ designer Biobrick will allow researchers to exchange sfGFP with any custom output desired. For example,  a LacZ reporter could be used with the to create conventional ‘Coliroid’ images. Additional fluorescent outputs such as RFP and CFP could be used to create separate and distinguishable signals. This will allow us to extend testing of red and green light sensors together on the same plate.

Additionally, we would test the tablet App using a blue light inducible construct for instance the LovTAP system presented in 2009 by EPF-Lausanne. Our app allows the simultaneous expression on three separate chromatic channels and is thus compatible with blue light systems. Ultimately,  these three signals could be used to create trichromatic output using RFP,  GFP and CFP to recreate a full color image, from black and white Coliroid to vivid color bacterial photography.

Finally, we are testing the tablet for it’s capacity to be used as a portable incubator and expression system based on it's heat output. Because of the high cost of purchasing a new incubator, we foresee this will be a boon to any iGEM team just starting out and will allow more teams to enter the competition and synthetic biology more accessible to high school programs. It also reduces the space requirements to run both educational and high-throughput expression experiments, as well as could be utilized in resource-limited settings for example to induce and record data from biosensors in remote locations. The app can be set up easily owing to the fact that many people already own a mobile tablet device and can turn it into an incubator by simply downloading it from the Google App Store.

Results Summary

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