The absence of phosphate (KH2PO4) provides the possibility to include alternative sources of phosphate, like P32 labeled components, or to select an optimal concentration of phosphate for certain yeast cell lines.
By omitting Potassium DiHydrogen Phosphate (KH2PO4), not only Phosphate (PO4-3) but also Potassium (K ) is omitted.
As a result yeasts are not only limited in Phosphate, but also in Potassium. This might cause problems in osmo-molarity and intercellular Potassium ion concentrations finally resulting in poor cell growth and low yields.
To avoid this problem an extra 550 mg/l (7.35 mM) of KCl is added. By adding this concentration of KCl the original concentration of K as present in YNB is restored. The extra addition of Chlorine is in almost all cases no problems to your cells.
Suspend 6.5 gram powdered medium in 1 litre distilled water
Store dry at room temperature