Making Liquid Media

— Christine Robbins 2018/11/14 14:00

Below are general directions for making liquid media. Please review them whenever making liquid stocks of media.

Notes:

• 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