Science educators use the Pioreactor to show their students hands-on biology

Woman in a biotech lab.

A pillar of biotech is understanding and scaling cell culture technology. This pillar has massive possibilities for our future too. For example, extracting biofuels from algae farms, and recent developments in cellular agriculture (cultured meats) will disrupt what we eat. Computer-aided protein design is happening now, and the scaling of production and extraction from microbial cells is still an engineering challenge. Students want to see the "full-stack" of biology today: book-led principles and hands-on practices. 

The Pioreactor is a great teaching aid to demonstrate both the principles and modern practices of microbiology and biotech. You can use it to study topics like microbial growth stages, fermentation, enzyme reactions, microbial resistance to antibiotics, to evolution. The Pioreactor can be deployed for many in-class experiments and tutorials, see below for some examples. 

High school level curriculum

Intro to microbiology

Students get a hands-on understanding of the lag, exponential and stationary phases of microorganisms, and the effect of nutrients and temperature on the growth. Students can observe a single Pioreactor, or groups of students can be given their own Pioreactor. Providing students with different types of media (like glucose, fructose, etc.), and varying temperatures, will give students intuition for the growth requirements for microorganisms. 

Example experiment: Yeast growth on varying temperature

Goal: demonstrate the effect of temperature on yeast growth. Students may have a prior belief that temperature effects are linear, ex: a culture at 10℃ will grow at half the rate compared to a culture at 20℃, and a third the rate at 30℃. This experiment would show the non-linear effect of temperature on growth (and relate it to how refrigerators halt spoilage for so long). Students and the teacher can pick temperatures to test beforehand.


Requirements:

  • At least two available Pioreactors
  • Dry baker's yeast 
  • YPD mix

Steps:

  1. Prepare a sterile stock of 10g YPD / 1L distilled water. Aim to make 20ml * the number of Pioreactors you are using (as each Pioreactor will require about 15ml)
  2. Once stock is cool, inoculate the stock with a very small amount of baker's yeast using best practices to avoid other contamination. Wait for the yeast granules to dissolve, aided by gentle rocking or stirring. 
  3. Mix well, and distribute up to 15ml of liquid to clean and sterilized Pioreactor vials.   
  4. Visit pioreactor.local and start a new experiment. 
  5. On the Pioreactors page, start Stirring activity, and OD reading activity
  6. Confirm that everything looks normal (ex: receiving optical density signal)
  7. Turn on Temperature Control activity. 
    Comparing maximum growth rate of yeast vs temperature.
  8. For each Pioreactor in use, change the temperature automation (under Settings) and provide the target temperature.
  9. Optional: you can change the names of the Pioreactor in the UI to display the target temperature. See docs here
  10. Students can watch growth progress on the Overview page. 
  11. After 24 or so hours (even sooner in some cases),
    the students can explore about maximum growth rates achieved, duration of lag phases, and overall
    yield of the cultures. Plotting these metrics vs temperature give students an intuition about how temperature affects yeast growth.

Example experiment: Culturing bacteria from yogurt

Goal: demonstrate the probiotic property of yogurt, and develop a yogurt starter. 

Requirements:

  • Pioreactor
  • yogurt
  • media 

Steps:

  1. Prepare media inside the Pioreactor's vial by heating it to boil and then letting it cool to room temperature.
  2. Added a very small amount of yogurt to the vial, and and place in the Pioreactor. 
  3. On pioreactor.local, turn on Stirring and Optical Density, and if all looks good, turn on Growth rate.
  4. To create an incubator, turn on Temperature Control, change the automation to PID Stable, and set a target temperature. 
  5. Observe how the culture grows over the next 12 hours. 
  6. The culture at the end is a representation of the culture in the original yogurt, and can be used as a yogurt starter. 

How bioreactors work

Students can be exposed to simple bioreactor principles: optical density, maintaining static environments, stirring, aeration, etc. We have also provided a cross section 3D print of the Pioreactor for a better understanding of how scattering works in the Pioreactor. 

Four photos of a cross section of a Pioreactor.

 

Students can also be introduced to some simple electrical engineering components as well: LEDs, photodiodes, Raspberry Pis, temperature sensors, motors and stirring, etc. The Pioreactor can easily be disassembled and reassembled by students. 

University level curriculum

Influence of nutrients on growth rates

Microbiology students can study the effect of how changing nutrients effects growth rate of yeast or bacteria. A practical lab may have the students prepare varying media, set up the Pioreactors, and after a few days, export the growth rates dataset. By comparing the composition of the media with the growth rate curves, students can perform an analysis of what the effect of specific nutrients may be.

Example experiment: Comparing how light conditions affect algae growth

Goal: demonstrate how varying both the intensity and composition of light on an algae culture will affect growth. Students can build and program their Pioreactor themselves to try to grow more algae than some baseline. Students may choose specific wavelengths of LEDs, varying intensity of LEDs, and different on/off cycles of the LEDs. 

Evolution

For a multi-week experiment, students can set up the Pioreactor in morbidostat mode, and study how evolution occurs in real time. For example, observing how yeast evolve higher salt-tolerance, or how bacteria evolve antibiotic resistance. If available, performing DNA sequencing on the original strain and the evolved strains lets students compare the pre and post genomes of the microbes. Read more about directed evolution

Electrical engineering or biotech labs extend the Pioreactor

For electrical engineering or biotech courses, students get to hack on the Pioreactor and extend its capabilities. Small computer programs can be written ontop of the Pioreactor's open API, too. 


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