So I decided to purchase a pharmaceutical grade mold and yeast medium from a large bio-science distributor. What a better way to test this stuff out than to do a little experiment.
Equipment:
- Accurate scale (grams)
- 500 ml measuring cup
- 100x15 Petri Dishes
- 15 and 30 ml vials with caps
- Pressure cooker (aka, autoclave)
- Mold and yeast Medium
- Parafilm
- 1000 W Microwave
Reagents:
1. Mold and Yeast Medium. Ingredients per liter:
- Maltose, Technical 12.75g
- Dextrin 2.75g
- Glycerol 2.35g
- Pancreatic digest of gelatin 15.0g
- Agar
pH after autoclaving 4.6 +/- 0.2 at 25C
2. Double distilled, deionized water, pH 7.0 at 25C
3. Wort plus yeast nutrients, 44GU, PH 5.43 at 65C
Procedure:
Media + water:
1. 4.20 g Yeast Medium was weighed and added to a 500 ml measuring cup.
2. DI Water was added to QS 125 ml. Solution was stirred.
3. Solution was placed in Microwave uncovered and set on High Power for 1.0 min.
4. Solution was removed, stirred and heated at high for another 1.0 min. Boiling detected.
5. Solution was removed, stirred and heated at high for another 30 sec to prevent boil over.
6. Solution was stirred. Solution was homogeneous and all medium was dissolved. Solution was clear, semi thick liquid.
7. Solution was deposited into Petri dishes (~20 ml), and glass vials (5.0 ml in 15 ml vials and 8.0 ml in 20 ml vials). Screw caps were loosely placed on vials for autoclaving.
Media + 44 GU Wort:
1. 4.20 g Yeast Medium was weighed and added to a 500 ml measuring cup.
2. 44 GU Wort was added to QS 125 ml. Solution was stirred.
3. Solution was placed in Microwave uncovered and set on High Power for 1.0 min.
4. Solution was removed, stirred and heated at high for another 20 sec. Vigorous boiling detected.
5. Solution was removed, stirred and heated at high for another 15 sec to prevent boil over.
6. Solution was stirred. Solution was homogeneous and all medium was dissolved. Solution was dark amber, semi thick liquid.
7. Solution was deposited into Petri dishes (~20 ml), and glass vials (5.0 ml in 15 ml vials and 8.0 ml in 20 ml vials). Screw caps were loosely placed on vials for autoclaving.
- Solutions were placed in Pressure Cooker Autoclave and cooked for 20 min at 15 psi:
Tubes and plates were removed from Pressure Cooker. Tubes were cooled on a slant (chop-stick was used to great angle).
The left over of the Medium + water was placed in a cup and allowed to solidify. The medium was un-molded. This will be exposed to ambient air for 12 hours and then incubated to be used as a positive control. One tube of each medium will be incubated to provided a negative control for each preparation:
- A batch of Old Medium in Wort (prep Mar2010) will be used for a comparison:
New solution will be allowed to set for 48 to solidify and to insure no contamination.
Once all solutions are stable, a yeast sample will be added to each dish and slant. A 10 ul serial single used loop will be used to collect know yeast sample. Known Yeast will be applied to plates in a "quadrant dilution" application. All samples will be photographed every 12-24 hours and colonies counted.
More to follow....
Jason
