Induction medium
0.2% (w/v) glucose
0.2% (w/v) casamino acids (vitamin assay quality; DIFCO)
20 μg/ml adenine
0.5 μg/ml thiamine
(Used to induce transcription of the phoA promoter) Combine the ingredients to a final volume of 1 liter in H2O. Sterilize by filtration and store at 4°C.
This low-phosphate medium was originally developed as a minimal salts medium for isotopic labeling. Although difficult to prepare, this medium consistently provides the highest level of induction.
