Hello,
I am preparing SOB media containing 20 mM MgSO4. I read several protocols that make me confuse.
Some recipe is MgCl2 (10 mL/L of 1M MgCl2) and MgSO4 (20 mL/L of 1M MgSO4).
Another is only MgSO4 (20 mL/L of 1M MgSO4).
But some is MgCl2 (10 mL/L of 1M MgCl2) and MgSO4 (10 mL/L of 1M MgSO4).
If the SOB media will be used for preparing competent cells, which recipe is the correct one.
I do appreciate your kind assistance in advance.
Thank you very much
Urai
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What is SOB containing 20 mM MgSO4 ?
Started by RNasefree, Dec 20 2010 01:04 AM
2 replies to this topic
#1
Posted 20 December 2010 - 01:04 AM
#2
Posted 20 December 2010 - 01:20 PM
SOB (super-optimal broth) with 20 mM Mg2+, composed of 10 mM MgCl2 and 10 mM MgSO4 is the correct formulation. Read Hanahan 1983, J. Mol Biol 166; 557-580 for more information.
#3
Posted 21 December 2010 - 07:12 AM
I think it is the total concentration of Mg2+ which is important, there are various different recepies using different salts to give the 20mM Mg2+ but they should all give similar results.