The Project to Increase Mastery of Mathematics and Science
Yeast Genetics Workshop
Materials and Supplies
YPD (YEPD) Media (yeast extract, peptone, dextrose)
Since YPD media is made from ground-up yeast, it contains all the nutrients that yeast cells need to grow (a form of microbiological cannibalism). It is considered to be a very rich media, and even cells that contain mutations in genes required for small molecule biosynthesis (i.e. amino acids, nucleotides etc.) can grow on it. Although different sugars can be used as an energy source, most commonly dextrose (glucose) is included at a final concentration of 2%. YPD media can be made as a liquid, or as a solid medium for plates through the addition of agar.
Since a host of microorganisms will thrive on YPD media, it is important to observe sterile technique when making and using the media.
Depending on the experiment, it may be necessary for you to incubate your yeast cultures at different temperatures. Warm (28 to 36 C) incubators can be improvised by placing a light bulb within a large bucket, and adjusting the position of the lid. Basements, fridges and window sills can be used for colder temperatures (10 to 18 C).
Preparing YPD Plates
Protocol for seperate ingredients
to a 1L Erlenmeyer flask, add
500 ml ddH2O
5g yeast extract
10 g Bacto-peptone
10 g bacto-agar
stir bar in flask
- stir and boil for 5 min. in microwave
- add 50 ml 20% dextrose
- boil 3 more minutes, pour Petri plates (makes about 15 plates)
Protocol for premixed dry media (70 g/L)
Take 300 mls of water and boil in large flask in microwave for 3 minutes
add 21 grams of pre-mixed media, mix and boil for 5 more minutes
pour plates and let solidify
-Layout plates in stacks of three. With one hand, remove bottom plate cover and all plates above. Keeping this hand partially over the empty dish, with the other hand pour the media until the bottom of the dish is covered. Replace cover immmediately and repeat for the next dish in the stack.If you have several different batches of plates to pour, put those flasks which will not be immediately used onto a hot plate/stirrer, setting 4 stir, setting 1 heat. This will retard media solidification.
- cover plates and let set upright at room temperature, 1 day.
- invert plates, let sit 1 day.
- examine plates and discard those which are contaminated and those with excess bubbles.
- store at in fridge.
Preparing YPD Liquid Media
Materials
stir plate
stir bar
1L erlenmyer flask
yeast extract
Bacto-peptone
Protocol
to a 1 L Erlenmeyer flask, add
500ml ddH2O
5 g yeast extract
10 g Bacto-peptone
-boil for 8 minutes, pour approximately 200 ml in 250 ml bottles
To purchase products related to these experiments:
Thomas Scienhtific
1-800-345-2100
1-800-345-5232 Fax
Yest extract
Cat no. C880-A08 500g
Bacto Agar
Cat no .C010-Q45 100g
Cat no. C010-Q48 1lb
Bacto Peptone
Cat no. C574-Q36 500g
Dextrose
Cat no. C263-G75 500g
Plates
Cat no. 3488-B28
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