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
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
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:
Saturday, Aug. 1
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...
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 also tried with sugar and ginger, then with only sugar and then without any sugar nor ginger.
Monday, Aug. 3
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
- 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:
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.