Rifampicin

Mode of Action

Strongly inhibits prokaryotic RNA polymerase and mammalian RNA polymerase to a lesser degree. Does not inhibit T7 RNA polymerase.

Mechanism of Resistance

Cells can spontaneously mutate to achieve resistance to Rifampicin.

Usage Notes

1. 50 mg/mL stock solution in methanol.
2. Vortex immediately to prevent rifampicin from sticking to bottom of tube.
3. Add ~5 drops 10 N NaOH per mL to facilitate dissolving.
4. Add 2 mL per liter of culture to achieve a working concentration of 100 μg/mL.

Alternately, dissolve 50mg/mL in DMSO and vortex to suspend. In this form, you don't need NaOH. Store at -20°C.

Rifampicin is light-sensitive so store stock solution, plates and media in the dark and wrap in foil. It also degrades in solution fairly quickly, so make stocks and replace them every couple months.

References

• A Short Course in Bacterial Genetics
• Molecular Cloning