M9 CA Medium

M9 CA Media contains the essentials for bacterial species to grow.

Glucose as a carbon source and casamino acids as a nitrogen source.

Important components of M9 CA medium are the carbon source from glucose, a nitrogen source from ammonia chloride, and electrolytes from sodium, chloride, potassium, calcium, phosphorus and magnesium salts in the M9 solution.

Applications
M9 CA Media is often used to define if a particular microbial species is a heterotroph, namely an organism that does not have any nutritional requirements beyond core sources of carbon (sugars) and nitrogen (to synthesize amino acids and nucleic acid bases).

Auxotrophs, or organisms with nutritional requirements will not be able to grow on minimal media. M9 CA medium supports the growth of recombinant strains of E. coli and wild-type strains of E. coli. Advantageously, M9 medium is inexpensive, low auto-fluorescence (when excited at 488 nm) and low absorbance M9 CA.

M9 Medium is used for the following applications: propagation of E. coli strains, maintaining positive selective pressure on recombinant strains of E. coli with plasmids coding for the ability to produce essential substances such as amino acids or vitamin, and maintaining stocks of F’-containing bacteria for use with M13 bacteriophage.

Recommendation
Supplementing M9 with magnesium and calcium will increase the growth of recombinant E. coli. Also, M9 can be supplemented with specific amino acids or other metabolites to allow for selection of specific auxotrophs