TYGPN Medium: TYGPN is a rich medium on which Escherichia coli will grow rapidly. This medium contains essential amino acids, nucleotide precursors, vitamins, and other metabolites that the cell would otherwise need to synthesize 1 . The main components of this medium are tryptone and yeast extracts, which provide the bacteria with the nitrogen and growth factors needed for replication. The addition of glycerol provides a carbon source and the sodium phosphate, dibasic and potassium nitrate helps to buffer the system against radical changes in pH due to metabolism. In this rich medium, a typical strain will double in number every 20 to 30 minutes 1.