[retrojohnnycanuck]

I am currently trying to culture a bacteria species called Akkermansia spp. The recommended method is to add 100 μL of the bacteria stock (in solution form) to a tube of Brain Heart Infusion broth containing mucin.

Firstly, I need to dissolve the mucin powder in 1M NaOH to make it soluble. It should be done at 20 mg (i.e. 0.02 g) of mucin powder to 1 mL of 1M NaOH.

Secondly, I need to add 2 μg/mL of the dissolved mucin to a tube containing 9 mL of Brain Heart Infusion broth. That means I need to add 14 μg of the dissolved mucin.

Problem: How much of the dissolved mucin (in μL) should I add to my tube of Brain Heart Infusion broth?

[Babcock_Hall]

I am not sure how you decided on 14 µg.  Can you show that calculation?

[retrojohnnycanuck]

I am not sure how you decided on 14 µg.  Can you show that calculation?

Sorry, had a typo there. It should be 18 µg (i.e. 2 x 9).

[Babcock_Hall]

Can you show your attempt to calculate the volume of mucin needed?

[retrojohnnycanuck]

Can you show your attempt to calculate the volume of mucin needed?

Yes. I set up the following equation:

[(20x)/(9+x)] = 2
20x = 18 + 2x
18x = 18
x = 1 mL

[Babcock_Hall]

If you took 1 mL of mucin solution with a concentration of 20 mg/mL, you would have 20 milligrams of mucin.  In a final volume of 10 milliliters, the concentration would be 2 mg/mL.  Offhand, I suspect that your calculation has some inconsistency in units

The final concentration (which I take to be 2 µg/mL) is quite a bit smaller than the stock concentration.  That means that you will need to pipet a very small volume.