10X M9 salts
1 Dissolve 6.8 g Na2HPO4¡¤7H2O, 3 g KH2PO4, 0.5 g NaCl and 1 g NH4Cl sequentially in 90 ml distilled water.
2 Make up volume to 100 ml with distilled water.
3 Sterilize by autoclaving and store at room temperature.