Hello Everyone,
I'm in the process of preparing to make several 20 Liter bottles of liquid culture media. The media contains a buffer, four carbon sources, amino acids, vitamins, and metals. I combine all the ingredients and then filter sterilize the medium. However, at the moment, I'm in the process of preparing only the metal solutions. My idea is to prepare a large, concentrated amount of metals, which I can then aliquot into smaller volumes that would be frozen and added to the medium during preparation.
My problem is that during the preparation of metal solution there is a large precipitation as soon as I add manganese chloride tetrahydrate. Here is a list of all the metals that I add to a solvent of sterile, demineralized water:
ammonium molybdate tetrahydrate 0.12 g
calcium chloride dihydrate 1.2 g
cobalt(II) sulphate heptahydrate 0.12 g
copper(II) sulphate pentahydrate 0.12 g
iron(II) chloride tetrahydrate 1.6g
magnesium chloride hexahydrate 80 g
manganese chloride tetrahydrate 1.6 g
zinc sulphate heptahydrate 0.12 g
I add the metals in the order that they are listed to 700 mL water, which I would eventually top off to 800 mL.
Does anyone know what is causing the precipitation and how to avoid it?
The pH of the solution up until I added manganese chloride tetrahydrate was between 4.5 and 5.0 (I can't remember exactly but it was definitely in that range). There was previously no precipitation.
Any help would be appreciated!
I'd try leaving CaCl2 out and checking if the remaining components can be mixed together. Calcium sulfate, which most likely forms in the mixture, has a low solubility in water.
Hi Cyrus,
I am not an expert in this field I have used Citrate to keep Fe3+ soluble in bacterial media. You might want to take a look at this paper http://wolfson.huji.ac.il/expression/local/bacteria/studierAutoInduced.pdf
Cheers David
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