YPD (YEPD) broth growth medium - 25g

YPD (YEPD) growth medium – 25 g powder for 0.5 litre

YPD (also called YEPD) stands for yeast extract peptone dextrose and is a nutrient-rich growth medium for yeast (Saccharomyces cerevisiae). It contains dextrose, peptone and yeast extract. Dextrose is the energy source, while yeast extract and peptone provide carbon, nitrogen, minerals, vitamins, trace elements and other nutrients that stimulate yeast growth. One pouch is dissolved in 500 ml of water.

YPD is commonly used in microbiology together with agar to make agar plates. These are useful for checking for contamination, making a starter, isolating yeast, growth tests and cell counting, and for getting an indication of phenotypic traits (what an organism visibly does differently from another).

Contents

• 1 pouch with 25 g of YPD powder
• For 0.5 L (500 ml) of growth medium

How to make liquid YPD

Dissolve one pouch in 500 ml of water and sterilise in an autoclave. Homebrewers can use a microwave to disinfect the contents in a borosilicate bottle with the lid slightly loosened. Avoid boil-overs. Take the bottle out and place aluminium foil around the neck. When the bottle has cooled to about 70°C, screw on the cap (not too tightly).

How to make agar plates

Equipment: 500 ml borosilicate bottle, YPD, agar and petri dishes. The recipe makes enough for 20 agar plates with a 9 cm diameter.

1. Weigh 10 g of agar (2%) and 25 g of YPD medium into 500 ml of room-temperature tap water in a borosilicate bottle, and let it swell for 15 minutes.
2. Bring the mixture to the boil in a microwave to disinfect it. Avoid boil-overs, and screw the cap on so that it gives a little.
3. Mix the solution gently without creating air bubbles, and cool the bottle to about 60°C.
4. Divide the mixture evenly between 20 agar plates, 25 ml per plate or to a height of just under 0.5 cm. Fill each dish halfway, place the lid on carefully and swirl the dish so the solution spreads out.
5. Let the plates set overnight. They are ready to use the next day.

Read our article (in Norwegian) on using agar plates.

Frequently asked questions about YPD growth medium

What is the difference between YPD and YEPD?

None. Both stand for yeast extract peptone dextrose.

How much liquid does one 25 g pouch make?

One pouch contains 25 g of powder and is dissolved in 500 ml of water.

Do I need agar?

Only if you want to make solid agar plates. For liquid growth medium, YPD and water are enough. For agar plates, mix 10 g of agar and 25 g of YPD in 500 ml of water.

Can I sterilise without an autoclave?

Homebrewers can use a microwave and a borosilicate bottle with a loose lid to disinfect the contents. This is not the same as sterilising in an autoclave, but is a common solution at home.

Related

• Measuring equipment and lab
• 500 ml bottle of 3.3 borosilicate glass, blue cap
• Petri dishes, sterile – pack of 20