Dorman:Intracellular Salts Medium

This media, described by Headley and Payne is formulated to contain ion concentrations similar to eukaryotic cells. Thus, gene expression is frequently quite different in this medium compared to media like L. For example, the spv operon of Salmonella is expressed in exponential phase in this media, while it is repressed in exponential phase in L (Wilson et al. 1997; Wilson and Gulig 1998)

To make the base of the media media, combine the following in ~800 mL of H2O:

34.23g K2HPO4-3H2O 2.72g KH2PO4-H2O 0.12g MgSO4-7H2O 1.05g K2SO4 0.27g NH4Cl 0.29g NaCl and 2&mu;L of 0.5M CaCl2

add H2O to a final volume of 1L and autoclave.

To use the media, add a carbon source, supplements and antibioics as required.

The origional paper uses 0.4% glucose, which I typically use as well.

That paper also adds nicotic acid, which is required for Shigella growth. I omit this when working with Salmonella. However, SL1344 and its derivitives are hisG, so histidine needs to be supplemented to a final concentration of 0.5 uM.

So add: 2.5 &mu;L of a 200 mM stock of histidine per mL of media.