Team:Paris Bettencourt/Notebook/Manufacturing

July 27th


Beginning of the manufacturing project! Let's do it!


Goal

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.

Procedure

  • 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)

July 28th

Goal

Our first idea to distribute the yeast is to dry them

Procedure

  • 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.

July 29th

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.

July 30th

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.

July 31th

Result of the second OD test:


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August 1st

Goal

The powder obtained with the drying method is full of static electricity and stick to everything, not very easy to distribute.
We are therefore looking fo other solutions...

Our second idea is to cook a powder

Procedure

(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 nor ginger.

August 3rd

Results of the second drying:
The survival rate is about 70%.

Milling and plating of the powder obtained with the potato recipe.

Tuesday, Aug. 4
While doing the recipe with the potatoes, we realise it wasn't easy to do and it took a lot of time and a lot of ingredients.
We decided to reduce the number of ingredients, using only water and rice flour.
Protocol:
  • Mix the yeasts with one cup of osmosed water
  • Add 2 cups of rice flour
  • Knead till you get a nice paste
At this point, we tought the paste could be shaped, instead of being milled in a powder.
  • Shape it in little cubes
  • Let it dry for few hours

The result is a small solid cube, very nice to give away. Several cubes can be packed together.
We tought it could be a good media of distribution.
We plated small amount of the cubes dissolved in water.

Wednesday, Aug. 5
Results of the potato powder:
Survival rate:
  • Wheat flour, sugar and ginger:
  • Rice flour, sugar and ginger:
  • Rice flour, sugar:
  • Rice flour:
We can see that the more ingredients we put, the more the yeasts survive.

Thursday, Aug. 5
Results of the cube:
The survival rate is about 6%.

Friday, Aug. 7
  • Choice of the strain of lactococcus lactis MG 13.63, containing the plasmid PSIP411, resistant to erythromycin at a concentration of 10µL/mL
  • Let's name this strain G1513
  • Experiment to correlate the OD of a solution of G1513/water with the concentration of G1513 cells alive in the solution

Monday, Aug. 10
Results of the OD test for G1513:
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Making new cubes containing Sc. M Cherry and G1513 to calculate the survival rate.

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