Recipe for FM Medium

Contributed by Jakob Franke August 7, 1992 and updated in September 1999. Published in Franke and Kessin 1977.

• FM can be made up from 4 stock solutions (amino acids, vitamins, salts, and trace metals) which can be stored indefinitely at -20°C . The composition of the stock solutions is given below.
  
• Glucose, phosphate, and dihydrostreptomycin-sulfate are added as solids.
  
• The medium can be autoclaved or filter sterilized and is stored in the dark at 4°C.
• Gibco-BRL has made a batch of the medium, and so has Sigma (cat. no. F-8787), but both batches are sold out as far as I know.
  The medium is still available from BIO101 (cat. no. 4115-025 for 1 pack to make 1 L; cat. no. 4115-075 for 10 packs, and 4115-095 for 100 packs).
• It seems that some people experience the formation of a precipitate in the medium upon standing. We have never seen this with either home-made medium or the Sigma medium.  Anyway, do NOT remove the precipitate, since the medium will not support growth if the precipitate is removed.

[INDEX]

• 250 ml 4x amino acids
• 50 ml 20x vitamins
• 20 ml 50x salts
• 0.1 ml 10,000X trace metals
• 10 g glucose
• 0.87 g K₂HPO₄
• 50 mg dihydrostreptomycin-sulfate

[INDEX]

• 4x amino acid stock (in 8 mM NaOH) (5 liters)
  
  • 1.6 g NaOH
  • 14 g arginine·HCl
  • 6 g asparigine
  • 4 g cysteine
  • 10 g glutamic acid
  • 18 g glycine
  • 6 g histidine·HCl-H₂O
  • 12 g isoleucine
  • 18 g leucine
  • 18 g lysine·HCl
  • 6 g methionine
  • 10 g phenylalanine
  • 16 g proline
  • 10 g threonine
  • 4 g tryptophan
  • 14 g valine
  
  
  The pH should be about 4.2.
  Adjust the volume to 5 liters and store at -20°C (we freeze 1/2 liter aliquots).
  Stick to the amino acid forms indicated, otherwise solubility problems will arise.
  


• 50x salts (1 liter)
  
  • 50 ml 1 M NH₄Cl
  • 1 ml 1 M CaCl₂
  • 50 ml 0.1 M FeCl₃
  • 20 ml 1 M MgCl₂
  
  
  Adjust volume to 1 liter and store at -20°C.
  


• 20x vitamins (1 liter)
  
  • 100 ml biotin (4 mg in 1 liter 10 mM NaHCO₃)
  • 20 ml cyanocobalamin (5 mg in 1 liter H₂O)
  • 100 ml folic acid (40 mg in 1 liter 10 mM NaHCO₃)
  • 100 ml lipoic acid (80 mg in 1 liter 10 mM NaHCO₃)
  • 100 ml riboflavin (100 mg in 1 liter 10 mM NaHCO₃)
  • 100 ml thiamine·HCl (120 mg in 1 liter H₂O)
  
  
  Adjust volume to 1 liter and store at -20°C.
  


• 10,000x trace metals (100 ml)
  
  • 4.84 g Na₂-EDTA·2H₂O
  • 2.30 g ZnSO₄.7H₂O
  • 1.11 g H₃BO₃
  • 0.51 g MnCl₂·4H₂O
  • 0.17 g CoCl₂·6H₂O
  • 0.15 g CuSO₄·5H₂O
  • 0.10 g (NH₄)6Mo₇O₂₄·4H₂O
  
  
  Adjust pH to 6.5 and volume to 100 ml. Freeze aliquots at -20°C.
  

[INDEX]