— Christine Robbins 2018/11/14 15:59

YEP Liquid Media is used to grow up yeast cells after a carbon source has been added. There are a number of variations including different carbon sources and drugs for selection of strains with deletions/markers.

Location:Stock Solutions are kept on shelf K and L

Notes:

• Please make sure that you add a carbon source before using the media (glucose, glycerol, raffinose, ethanol, etc.). When you add a carbon source be sure that you label the bottle with the final concentration of the carbon source, the date, and the initials of who added it.
• YEP stocks should not be stored with drugs. Please add the appropriate volume to only the amount of media you need.
• Whenever using media, please remember that if you open the last bottle, you need to make more right away. Not later. If you are a student and you must leave for class, please let your friendly neighborhood Lab Tech or Lab Aide know that the media needs to be made
• It is always recommended that you print out the media recipe and cross off every item as you add it to avoid mistakes
• Carbon sources should always be added after autoclaving as the media is being used

• Grab the appropriately sized, sterilized beaker and bottles from the glassware shelves
  • For liquid media, a beaker the same size as your final volume is sufficient
  • You will only fill bottles to the last labeled volume, for example: A 1L bottle is only labeled to 900mL, therefore you will only fill it to 900mL
• Label all glassware with the name of the media you are making, your initials and the date (yes, this includes the beaker)
• Place a stir bar in the bottom of the beaker
  • The stir bar should be approximately 1/3 the diameter of the beaker
  • When removing the stir bar from the autoclave pouch, remove it by pushing it out, not by sticking your fingers in and grabbing it.
• Add MilliQ Water to approximately 1/4 the final volume using a graduated cylinder and turn on the magnet on the hot plate
• Weigh out the reagents listed on the recipe and add them to the media one at a time
  • It is best to add all reagents slowly to avoid clumping
• When all ingredients have been added, fill the beaker to the final volume with MilliQ Water using a graduated cylinder
• When all ingredients are incorporated, pour the media into the labeled bottles
  • You will only fill bottles to the last labeled volume, for example: A 1L bottle is only labeled to 900mL, therefore you will only fill it to 900mL
  • Please pour carefully and avoid pouring out the stir bar
• Cap the bottles so that the caps still wiggle, but do not come off (allows steam to escape without having exploding bottles
• Place a piece of autoclave tape over the top of the cap and down the side of the bottle as seen in the image
• Autoclave the bottles on the liquids cycle
• While the autoclave is running, clean up
  • Clean up the chemical bench and scales with water followed by 70% EtOH
  • Throw away any used weigh boats
  • Wash the beaker and lab scoops
• When the autoclave is done, remove the bottles
• When the bottles have cooled, screw the cap on completely and place them on the shelf where they belong

Directions

• Get a beaker, and bottles and place a stir bar in the beaker
• Label all bottles and beaker with YEP, your initials and the date
• Add MilliQ Water to about 1/4 of your final volume
• With the bar stiring, add the reagents that will be added before autoclaving
• After all of the reagents are incorporated, fill the beaker to the final volume
• Pour the media into labeled bottles (only fill to the highest marked volume on the bottle. Example: a 500mL bottle only has gradations to 400mL, so only add 400mL media)
• With the caps partialy screwed on (you should be able to wiggle them without them coming off), label with autoclave tape
• Autoclave on setting 4 with some water in the tray
• When cool, screw caps on completely and store
• Only add carbon sources when opening a bottle for the first time. Remember to note the addition

YEP Recipe

YEP is the backbone recipe for most yeast medias. All recipes below this will be variations with difference carbon sources or drugs added when the bottle of YEP is opened and used for the first time.