Yeast is cultured by growing it on solid agar plates or in liquid culture.
Here's a more detailed breakdown:
1. Solid Agar Plates:
- Preparation: Solid agar plates, typically 9 cm in diameter, are prepared by filling Petri dishes with a solidified nutrient-rich media. This media provides the necessary food for the yeast to grow.
- Inoculation: A plastic disposable loop is used to streak the yeast onto the surface of the agar plate. Streaking involves dragging the loop across the agar in a pattern to separate individual yeast cells.
- Incubation: The plates are then inverted (to prevent condensation from dripping onto the culture) and placed in an incubator. The incubator is maintained at a controlled temperature, usually between 25°C and 30°C, which is optimal for most common yeast species.
- Growth: Over time, individual yeast cells multiply and form visible colonies on the agar surface. These colonies typically appear as small, raised, and often circular growths, reaching approximately 1mm in diameter.
2. Liquid Culture:
While the provided reference focuses on solid media, it's important to note that yeast can also be cultured in liquid media. This involves:
- Preparation: A sterile nutrient broth is prepared in a flask or test tube.
- Inoculation: A small amount of yeast is added to the liquid broth.
- Incubation: The flask is placed on a shaker in an incubator at a controlled temperature. Shaking provides aeration, which is important for yeast growth.
- Growth: The yeast cells multiply in the liquid media, resulting in a cloudy suspension. The density of the culture can be monitored using a spectrophotometer.
In summary, yeast culturing generally involves providing a nutrient-rich environment (either solid or liquid) and maintaining optimal temperature conditions to promote growth.
