So My Friend Made Me A Bioreactor...

Testing David Jordan's tabletop bioreactor.

Drop David an email at david [at] livingphysics [dot] org for enquiries / purchasing!

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My friend David Jordan built me a modular bioreactor. It ended up being really easy to use and it works! On my desk top at home! Here are my notes on testing it.

A bioreactor is something that monitors and controls biological media. This allows us to do experiments in a controlled environment. Bioreactors traditionally are a complicated and expensive piece of equipment, but the awesome thing that David did was to make one that’s super easy to use that fits on my table.

Here it is, with my finger for scale…

The bioreactor with algae inside.

David’s bioreactor has a compartment to put a vial of biological media inside it. Then there’s a gas sensor that screws on top to complete the seal. Once the vial is inside the compartment, there are sensors to measure things. And also pieces that control the environment, like light and heat. The sensors and the environment components are all connected to a Raspberry Pi which can be automated or operated remotely.

This particular bioreactor has a few sensors

• a CO2 concentration sensor

• an O2 concentration sensor

• a temperature sensor

• an optical density sensor to see how cloudy the water is to track population growth.

Then there are components that change the environment of the vial.

• There is a heating element to control the temperature.

• There is an LED to expose the vial inside to light.

The sensors, heating element and LED are connected to a Raspberry Pi computer. On the Pi, theres a python script that records the reading of each element. David wrote a script, but it’s fully customisable and you can ssh into it too like a regular server. Robot lab geeks take note.

For the first experiment, I put some algae in some growth media. To prevent contamination I used my cheaper laminar flow hood, which pumps out HEPA filtered air over the workspace. Here’s a picture of me getting the algae out.

Then I put the algae in growth media and then screwed the gas sensor on top:

Sliding the vial into the compartment:

Then I turned the bioreactor on by hooking up the raspberry pi to a monitor, keyboard and mouse. Overall, super easy to set up. You can see the measurements on the monitor.

It works!

The first thing to try was turn the light on and off in 12 hour cycles. This was done with a python script, which also was used to regulate the temperature. So I started the bioreactor, turned on the sensors, turned on the light cycle, and the heating element kept the system at constant temperature.

And what did I observe?

The algae did photosynthesis and respiration!

The graph shows the oxygen and CO2 concentration during the periods where the light was off and on. The dark region shows when it’s off. When it’s dark, in the beginning, you can see the CO2 rising and the oxygen concentration falling. And then it’s light, it flips. Pretty cool! The CO2 eventually goes to zero but you can see the oxygen concentrations fluctuate.

The optical density plot is a proxy for the density of the species, which is also recorded. And you can see also that the bioreactor kept the temperature constant pretty well.

Above all, this bioreactor was super easy to set up, and easy to use. It makes me feel excited about the possibilities of being able to do science more easily. I’m also more optimistic about the role of table top, safe experiments for independent scientists.

David and I have spoke about the modularity of this design. I think a bioreactor has a cool interpretation in that you’re viewing life forms not as themselves, but through the macro variables of the environment that they are in. I’ve written a lot about state variables and phase space, both in thermodynamics and biology, and think there are a whole host of interesting things to explore along these lines with a bioreactor on your table top.

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Acknowledgements

Thank you again to David Jordan for his generosity,