From ActinoBase

IMA (Instant Mash Agar)

IMA is sometimes also called Smash (after the brand name of the instant potato commonly used). Other brands of instant mashed potato can also be used to make up this medium.

David Widdick initially conceived the idea of using instant mashed potatoes for the cultivation of the potato pathogen Streptomyces scabies. (Perhaps unsurprisingly, S. scabies does indeed grow particularly well on IMA.) The initial formulation contained 50g/L Smash and 12g/L agar[1], but later formulations follow this recipe (20g/L Smash).[2]

IMA is also suitable for the growth of other Streptomyces sp. Strains of Streptomyces coelicolor that fail to sporulate well on SFM may sporulate better on IMA.


Per 100 mL:

  • 2g Smash instant potato
  • 2g agar
  • 100mL tap water


  1. Mix all the components together well in a 200mL Erlenmeyer flask with a bung, or other container suitable for autoclaving.
  2. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
  3. Mix well and pour into sterile Petri dishes.



  • Because the agar and instant mashed potato are not very soluble, IMA should be made up in small 100 mL batches (do not attempt to make up 1 L and aliquot into flasks for autoclaving)


[1] Joshi, M. V., Mann, S. G., Antelmann, H. , Widdick, D. A., Fyans, J. K., Chandra, G. , Hutchings, M. I., Toth, I. , Hecker, M. , Loria, R. and Palmer, T. (2010), The twin arginine protein transport pathway exports multiple virulence proteins in the plant pathogen Streptomyces scabies. Molecular Microbiology, 77: 252-271. doi:10.1111/j.1365-2958.2010.07206.x

[2] Widdick, D. A., Hicks, M. G., Thompson, B. J., Tschumi, A. , Chandra, G. , Sutcliffe, I. C., Brülle, J. K., Sander, P. , Palmer, T. and Hutchings, M. I. (2011), Dissecting the complete lipoprotein biogenesis pathway in Streptomyces scabies. Molecular Microbiology, 80: 1395-1412. doi:10.1111/j.1365-2958.2011.07656.x