Hickey-Tresner agar (HT)
This medium was developed by Hickey and Tresner for the growth of some Streptomyces sp. that did not sporulate well on Bennett's medium. They found that the addition of cobalt improved sporulation of S. fradiae, while adding zinc or iron (instead of cobalt) decreased sporulation.
- 20 g agar
- 1 g yeast extract
- 1 g beef extract
- 2 g NZamine A
- 10 g dextrin
- 20mg CoCl2*6H2O
- up to 1000mL dH2O
- Combine all components and mix well.
- Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
- Sporulation of strains that sporulate poorly on other growth media
- Morphological differentiation (many organisms produce distinctive pigments on this medium)
 Hickey, R. J., & Tresner, H. D. (1952). A cobalt-containing medium for sporulation of Streptomyces species. Journal of bacteriology, 64(6), 891–892.
 Kieser, T., Bibb, M.J., Buttner, M.J., Chater, K.F. and Hopwood, D.A. (2000) Practical Streptomyces Genetics: John Innes Foundation, Norwich Research Park, Colney, Norwich NR4 7UH, UK