August

August 5th

The goal is to select a bacteria able to develop on 2-nonenal. We made 2 new media:

1) M9 Minimal Media 100% Glucose

• 200mL M9 Salts
• 0.1mL CaCl2 1M
• 2mL MgSO4 1M
• 20mL Glucose 20%
• Water: bring to 1L

2) M9 Minimal Media 50% Glucose - 50% 2-Nonenal (according to the number of carbon atoms)

• 200mL M9 Salts
• 0.1mL CaCl2 1M
• 2mL MgSO4 1M
• 10mL Glucose 20%
• 10mL 2-nonenal 10,7%*
• Water: bring to 1L

3) M9 Minimal Media 100% 2-nonenal

• 200mL M9 Salts
• 0.1mL CaCl2 1M
• 2mL MgSO4 1M
• 20mL 2-nonenal 10,7%*
• Water: bring to 1L

We autoclaved 6 bottles (2 of 500mL for each)

Then, we made liquid culture of C.striatum in media 1) to try if the minima media works.

* Concentration of the 2-nonenal solution: In M9 Media, we use 20mL of Glucose 20% (200g/L). The concentration of glucose is C=200/M=1.09 mol/L. Glucose has 6 carbons while 2-nonenal has 9, so we need 2/3 of the glucose volume to have the same amount of carbon atoms. C=2/3*1.09=0.74 mol/L and then 0.74*M=103.7g/L. That's why the concentration of the 2-nonenal solution is 10.73%. We also added Tween80.

August 6th

We poured 20 plates of each of the 3 media with 350mL of an agar solution and 100mL of medium.

Then we used 3 plates of each type to culture skin bacteria from 3 spots: arm, armpit and forehead. Ursczula sampled bacteria from her skin with a loop and for each spot she diluted the bacteria in 300uL of NF Water. Then we plated 100uL of each solution in each of the 3 types of plates and incubated them at 37°C.

	M9 100% glucose	M9 50%-50%	M9 100% 2-nonenal
Arm	x	x	x
Armpit	x	x	x
Forehead	x	x	x
NEB (control)	x	x	x

August 8th

After 2 days, nothind has developped on the M9 plates. M9 media is actually really slow for the development of any strain. That is why we created a new media which would be like the real skin environment: synthetic sweat according to this recipe

Fatty acids seem to be the main source of carbon so we replaced them by 2-nonenal.
We made 2 media:
1) without fatty acids
2) without fatty acids and with 2-nonenal mixed with 10% of Tween 80.

August 11th

Results of M9 plates

	M9 100% glucose	M9 50%-50%	M9 100% 2-nonenal
Arm	Many very small colonies	6	0
Armpit	Many very small colonies	0	0
Forehead	27	5	0
NEB (control)	Many	many	0

September

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October

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