Will magnesium (Mg2+) increase the cell densities for commonly used bacterial E.coli growth media?
Yes. Mg2+ can increase the cell density for LB, 2x YT, TB, and SB. The commonly used Mg2+ concentration is 10 to 20 mM. Either MgCl2, MgSO4, or both of them may be used. In addition, the aeration or the shaking speed of the incubator has to be increased at the same time. The normal shaking speed range of 150 – 250 rpm should be increased to a range of 350 – 400 rpm to obtain significant cell density increase. SOB and SOC contain sufficient amounts of Mg2+. Adding Mg2+ to these media will not further increase cell density.
