Table 2:

Stock solutions for M9 Medium

Component	Stock concentration	Mass	Stock Volume	Sterilization	Suggested storage conditions
19aa (5x)*	250 mg/L each aa	125 mg each aa	500 mL	Sterile filter	4 °C, 1 month
Proline (5x)	250 mg/L	125 mg	500 mL	Sterile filter	4 °C, 1 month
M9 salts (5x)	8.5 mM NaCl 18.7 mM NH4Cl 22 mM KH2PO4 47.8 mM Na2HPO4	2.5 g NaCl 5.0 g NH4Cl 15.0 g KH2PO4 64.0 g Na2HPO4·7H2O	1 L	Autoclave	RT
Glucose (10x)	20%	36.03 g	1 L	Sterile filter	RT
Biotin (100x)‡	1 mg/mL	12 mg	12 mL	Sterile filter	Use day-of
Thiamine (1,000x)	35 g/L	420 mg	12 mL	Sterile filter	Use day-of
FeSO4 (1,000x)	3 g/L	66 mg FeSO4·7H2O	12 mL	Sterile filter	Use day-of
MgSO4 (1,000x)	1 M	2.95 g MgSO4·7H2O	12 mL	Sterile filter	RT
CaCl2 (1,000x)	0.1 M	147 mg CaCl2·2H2O	12 mL	Sterile filter	RT
Trace metals (10,000x)§	10 mg/L each metal	3.9 mg CuSO4·5H2O 3.6 mg MnCl2·4H2O 4.4 mg ZnSo4·7H2O 1.8 mg (NH4)6Mo7O24·4H2O	100 mL	Sterile filter	RT
Water				Autoclave	RT

^*Stir ~1hr on stir plate at room temperature (RT) for all amino acids to dissolve.

^‡Add ~10 μL of 10 M NaOH to fully dissolve biotin before sterile filtering.

^§It is recommended to prepare the trace metals solution as a 100,000x stock in 10 mL, then dilute 1 mL 1:10 with H₂O to obtain a 10,000x stock solution.