Saccharomyces cerevisiae Rho-

The Saccharomyces cerevisiae Rho- yeast strains are delivered lyophilized in a glass vial. They are accompanied by a tube of sterile water of about 2 ml for yeast reactivation.

Reactivation of yeast and culturing on a Petri dish:
- Add 2 to 3 ml of sterile water to the tube of lyophilized yeast to suspend the yeast.
- Vortex the yeast solution.
- Using an inoculation loop, spread the yeast on YPG medium (ref. 107122) on a Petri dish.
- Incubate for 2 to 4 days at 37°C to obtain Rho- yeast colonies.
At this stage, the yeast concentration is probably too high for good visibility of colonies (CFU) on the Petri dish. To obtain well-separated colonies, suspend 2 colonies in a 2 ml tube of sterile water (approximately 1 colony of 1 mm for suspension in 1 mL of sterile water) and repeat the spreading protocol on a new Petri dish.

Another alternative: Prepare suspensions of known yeast concentrations at 10^3 cells/ml by counting beforehand using a Malassez cell.

The product consists of:
- 1 glass vial containing 0.2 g of lyophilized yeast
- 1 tube of 3 mL of sterile water