I just came across premade NGM (Nematode Growth Medium). It is a powder mix but has Cholesterol to be dissolved with water, then autoclave. My lab always uses the original recipe. We always add Cholesterol after autoclave.
Is Cholesterol autoclavable?
The powder formula I saw is:
Agar 17.5 g/l Sodium Chloride 3.0 g/l Peptone 2.5 g/l Cholesterol 0.005 g/l
What I usually do is I take 0.8g of cholesterol mix purchased from Sigma and dissolve it in 32ml pure ethanol.
Because I usually prepare a liter of solution, I take 1ml of the dissolved mix and add it to the 1L solution. It is important to note that it should be all stored in no less than 37 degrees and even 42 degrees Celsius. Cholesterol may crystalize again if cooled.
Sterols undergo pyrolysis when autoclaved (Article Pyrolysis gas chromatography of some sterols
). As they are hydrophobic it is best to dissolve in ethanol. Store frozen to reduce oxidation rates and just redisolve by vortexing before use.- Badges
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