The Environmental Simulation System
As we further developed our project, we ran into several issues - the foremost of which was the lack of any equipment in our lab that we could use to test the effectiveness of our modified cells against UV-B radiation. Much of the equipment in lab which utilizes UV radiation does so at the UV-A and UV-C spectrums and not specifically at the relatively narrow range from 285-315 nm. This left us in bit of a pickle: how could we test our cells without our light source specifically emitting UV-B radiation? Our solution was to design a new piece of hardware, which we dubbed the Environmental Simulation System.
The Environmental Simulation System (ESS) is a suite of useful unit operations which includes: (1) a lamp producing UV-B radiation; (2) a miniature orbital shaker; and (3) a temperature control system. By combining these functionalities into an enclosed, table-top system, we were successfully able to create an inexpensive alternative to the traditional incubation chamber required for basic biological work.
UV Exposure Lamp
When selecting a method of UV exposure, we had to compare several types of light sources including simple UV light bulbs and expensive UV LEDs. For our applications we needed a light source that would only emit light in the UV-B spectrum. The vast majority of "UV-B" light sources on the market today expose mostly UV-A or UV-C light, and so we were greatly limited in the devices we could modify for our purposes. We settled on a reptile lamp purchased from a local pet store. Often used in reptile tanks for household lizards, UV-B reptile lamps help to regulate vitamin levels in your average cold-blooded pet and worked nicely for our purposes. We confirmed that the lamp produces enough radiation to kill E. Coli cells through the ESS control tests (see Results), which show that cell death is directly correlated to longer exposure under our lamp.
Miniature Orbital Shaker
We also constructed an orbital shaker based on a previously drafted designwhich would allow us to grow liquid cultures outside the 37 degree room while exposing exposed to UV radiation. In producing this part we made several modifications to the original design. We developed our own Arduino code to control the stepper motor for the overall mechanism in order to customize the speed at which we could shake our cultures. While this shaker was only designed to work with a single Erlenmeyer flask, the design could be slightly updated to accommodate different sized flasks and culture tubes.
Temperature Control System
Finally, we built a simple temperature control loop into our ESS to incubate our cells at optimal growth temperatures. Run by an Arduino microcontroller, this system can be built to accommodate several common incubation temperatures found above ambient temperature such as 30 degrees Celsius for cyanobacteria or 37 degrees Celsius for E. Coli. With this feature combined with our orbital shaker, our Environmental Simulation System has the potential to operate as a tabletop version of the incubation rooms required for E. Coli or Cyanobacteria labs. Not only is this a remarkable achievement that could be employed by community labs and amateur biologists everywhere, but it may also be useful for future iGEM teams to use if they do not have access to the lab space necessary for growing E. Coli, cyanobacteria, or whatever other organisms they plan to work with for their projects.
As we were building the Environmental Simulation System, we decided early on in development that we would like to keep the cost low, not only so as not to break the bank, but also so that our design would be a feasible incubation alternative for other teams to use in the future. Below is a table listing all the costs associated with our design:
Thus our entire system costs roughly $150 to construct, far less than similar products to be bought from other vendors with or without temperature control. And while we are not suggesting that our design is by any means a perfect replacement to products which come from the likes of Sigma-Aldrich or Thermofisher, we do have evidence to suggest that it would be suitable for the basic culturing needs of any biologist.
Mechanism Description and Instructions
Below are links to instructions for building the ESS as well as a mechanism description for the overarching box around the system.
Temperature Control Directions (modified slightly from this design for Temperature rather than humidity control)
Instructions for Programming Stepper Motor (used for shaker)