From ActinoBase

Salt Peptone Yeast Agar (SPY)

Salt Peptone Yeast agar is a metal-rich media used to stimulate the activation of cryptic biosynthetic gene clusters as part of antibiotic discovery.


Per Litre:

  • 30g Soluable Starch
  • 15g pancreatic digest of casein
  • 15g peptic digest of animal tissue
  • 2g Yeast Extract
  • 10g MgSO4
  • 50mg CaCl2
  • 30mg ZnSO4
  • 25mg FeSO4
  • 16mg CuSO4
  • 12mg MnSO4
  • 20g agar
  • NaOH (to adust pH)
  • 1L dH2O


  1. On a heated stiring block, warm the water and add the pancreatice digest of casin, the peptic digest of animal tissue, the yeast extract and the trace elements.
  2. Add 2g of agar into each of 10 250mL conical flasks.
  3. Use NaOH to adjust the pH of the solution to pH 7.2.
  4. Dissolve the soluable starch in the solution. It can take a while for the starch to dissolve.
  5. Pour 100mL of solution into each flask.
  6. Autoclave



  • To dissolve the soluable starch, it is often required to make the media on a hot plate. Do not allow the solution to boil.
  • To add the trace elements, it may be easier to make concentrated stock solution which is then added to the media prior to pH adjustment.


Imai, Y., Sato, S., Tanaka, Y., Ochi, K. and Hosaka, T. (2015). Lincomycin at Subinhibitory Concentrations Potentiates Secondary Metabolite Production by Streptomyces spp. Applied and Environmental Microbiology, 81(11), pp.3869-3879.