Team:Paris Bettencourt/Notebook/Manufacturing

Monday Jul. 27
Beginning of the manufacturing project! Let's do it!

  • Choice of the strain of yeast: Sc. M Cherry, wich is resistant to geneticin at a concentration of 200µL/mL, and produce RFP

We will have to calculate a survival rate so we have to be able to know how many cells we have in the first place for each experiment:
  • Centrifuge the culture tube
  • Throw the media away
  • Replace it by a known quantity of osmosed water
  • Take the OD, doing the blank with osmosed water
  • Make dilutions of the yeasts/water solution to plate them
  • Deduce the concentration of Sc. M Cherry corresponding to 1 OD
First try today and plating of the different dilutions on YPD agar+ GEN (200)

Tuesday, Jul. 28
First idea: drying the yeasts
Protocol:
  • Centrifuge the culture tube
  • Throw the media away
  • Add a very small amount of water to detach the yeasts from the tube easily
  • Spread on aluminium
  • Let it dry for 2 hours
  • Scratch the aluminium to detach the dried yeasts
  • Plate the powder obtained to see if Sc. M Cherry survived
Results:
The aluminium is not a good idea, the yeasts stick to it and it gets destroyed when we scratch.
We have to find another drying paper.

Wednesday, Jul. 29
Result of the first OD test:
The 10mL solution of yeasts/water had an OD of 2,557 and 100µL of the 10^-4 dilution grew 359 colonies, so:
1 OD = 1,4x10^7 cells/mL
We launched a similar experience for more repetitions.

Thursday, Jul. 30
Results of the drying:
Yeasts grew in the plate. We can check that they produce RFP, it's Sc. M Cherry who survived.
Let's repeat the experience but drying the yeasts on a plastic dish.
This time, we took the OD and plated a known quantity of the obtained powder to be able to calculate the survival rate.

Friday, Jul. 31
Result of the second OD test:

Monday, Aug. 3
Results of the second drying:
The survival rate is around 70%.
But the powder obtained is full of static electricity and stick to everything, not very easy to distribute.
We are therefore looking fo other solutions...
Second idea: Cooking a powder
Protocol (found here: http://www.instructables.com/id/Stop-Paying-for-Yeast-Make-Your-Own/)
  • Cook some potatoes
  • Save the cooking water, wait till it's not too hot and mix 1cup of it with the yeasts
  • Add 1 cup of flour, 1 cup of sugar, 2 cups of mashed potatoes, a teaspoon of ginger/li>
  • Add 4 cups of cornmeal
  • Let it dry for 1 day
  • Mill the paste to obtain a powder
  • Plate the powder obtained to see how many Sc. M Cherry survived
We decided to try with wheat and rice flour to see if there is a difference. Since the product is designed for rice fermentation, using rice flour would be better!
We also tried with sugar and ginger, then with only sugar and then without any sugar or ginger.

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