MYPG (Malt Yeast Peptone Glucose) is the first culture media that I decided to prep for growing wild yeasts. The recipe is ideal for culturing Sacc and Brett in a lab setting. The mix contains DME, yeast extract (serves as nutrient source), Peptone (digestion of animal protein and provides amino acids), and glucose and used the recipe from the Brettanomyces Project. One could make this at home but you have to order the yeast extract and peptone as these are only available as lab grade reagents.
The recipe (for 500 mls):
- 1.5 g of DME
- 1.5 g of yeast extract
- 1.0 g of peptone (often called Bacto Peptone)
- 5.0 g of glucose.
- Dissolve in 500 mls of water
This is fine for liquid media, but if you want to make plates you have to add:
- 7.5 g agar
This mixture was autoclaved for 30 minutes to sterilize and poured into in petri dishes. I added a stir bar before I autoclaved and put it on stir plate to cool. While it was cooling I added:
- .011 g of Bromocresol Green
Supposedly, wild yeast are able to metabolize this dye but Sacc cannot. Therefore, wild yeast colonies would look clear white on the plate but not Sacc. Also, the dye is a pH indicator and turns clear in the presence of acid, a byproduct of wild yeast.
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There are other selective media, but for now I will try Bromocresol Green.
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