Articles, Blog

Media Prep

August 27, 2019

In order to grow, cells need very
specific environmental conditions food, energy, proper temperature and humidity. When growing cells in the lab we have to
create these conditions using culture media. Solid culture media is a mixture of agar
and nutrients poured into petri dishes. In this exercise we’ll demonstrate the
steps for preparing brain heart infusion agar. Always check the lot number and
expiration date. The right panel lists the composition of
the media and the final pH. First, add 100 mL of deionized
water to a graduated cylinder. Place a stir bar in a
250 mL flask. For the next steps we need an analytical
balance. Place a weigh boat onto the balance pan. Press the tare key to zero out the
weigh boat. Use a lab scoop to add 5.2g
of brain heart infusion agar to the weigh boat. Now add the powder to the flask. Add about 75 mL of
deionized water. Place the flask onto a stir plate. If you’re using a combination hot plate
and stir plate, be sure that the heat is turned off. After about 2 minutes, add the
remaining 25 mL of water from the graduated cylinder. Stir the solution until all of the
visible clumps have been broken down. Cover the flask with aluminum foil. We’re using foil cupcake wrappers
because they’re the perfect size. Place a piece of autoclave tape over the
foil and label it with the media name. Next use the autoclave to sterilize the media. The heat from the autoclave will also
help the agar to properly dissolve in the water. Power on the autoclave and make sure the
drain valve is closed. Add deionized water to the level
indicator line. Place the flask of culture media into
the basket, insert the basket, close the lid, and turn the handle to
create and airtight seal. Use the control panel to set the mode to
“sterilize,” the temperature to 121 degrees celsius. We’ll run this cycle for
17 minutes. While it’s running enter the date and time and the
operation details in the log and initial. Once the cycle ends and the pressure
gauge reads 0 PSI, use heat resistant gloves to slowly open the lid
and remove the sterilized flask. Back at the bench, place the flask onto the stir plate and stir the media very gently. Allow it to cool to about
45-degrees celsius. Pour the media into the petri dishes. The amounts don’t have to be exact, but be sure to cover the entire bottom
surface which is about 20 mL for standard size
petri dishes. Once the media has cooled it will
solidify and turn opaque. Here you can see the difference. The petri dish on the left has set up
properly. Turn the plates upside down to prevent
moisture from condensing on the agar surface, and store them in a
plastic bag until you’re ready to use them.


  • Reply krunal patel December 14, 2012 at 5:01 pm

    for pouring purpose use laminar air flow. not in normal desk.

  • Reply Belbras May 28, 2013 at 12:52 pm

    interesting the advice on avoiding condensation in the petri dishes

  • Reply Mariam Lotfy October 6, 2013 at 10:48 pm


  • Reply YummiestOrphan October 25, 2013 at 12:25 pm

    Why are agar plates (with micro-organisms on) only incubated for between 24 and 48 hours?

  • Reply Microman87954 November 26, 2014 at 2:15 am

    If the specimens are incubated for too long, the agar can dry out and the organism will likely die.

  • Reply roche mahinay April 24, 2015 at 5:47 pm

    opening the petri dishes widely will cause contamination. The procedure did not perform aseptic technique during the dispensing.

  • Reply Waqas Ul Hassan October 12, 2016 at 7:46 am

    thanks for help but somebody tell me more details

  • Reply Braiden Oborn October 20, 2016 at 10:58 pm

    That's a lot of effort for 3 dishes.

  • Reply Diyaa Razaq November 7, 2016 at 10:30 pm

    like it very nice and easy work 🌸

  • Reply Stay Wild Media December 10, 2016 at 5:36 am

    thats some fancy equipment…ill use my range top and a spoon

  • Reply Lajos Winkler December 26, 2016 at 6:17 pm

    Huge mistake there – not wearing a hair cap and having loose hair flap around. It might be ok if you're using a laminar flow cabinet, but if you aren't, it's totally wrong.

  • Reply Mohamed acro December 27, 2016 at 6:02 pm


  • Reply Brian Harrington March 2, 2017 at 6:23 pm

    Good work!

  • Reply Baha AliN March 14, 2017 at 10:09 pm

    good job

  • Reply Honey Singh May 18, 2017 at 11:54 am

    she poured the media into petri dishes in open environment…should be done in laminar or other aspectic conditions

  • Reply Katherine Manrriquez June 1, 2017 at 7:07 pm

    I feel like this makes it look more complicated than usual. Of course I make media for college teaching classes that don't need the exact measurements and sterility of a research lab. If your going to go the way of making it super precise, why not go all the way and use a vent hood to pour the media and create a sterile environment. Plates also shouldn't be opened up so much when pouring as the plate should have come in sterile beforehand​ and opening them that much will allow microbes in the air to land in the plate easier.
    But I will say this is great for giving my friends an idea of what I do all day because it's hard to explain without being able to show them.

  • Reply RAVI SINGH June 18, 2017 at 9:05 pm

    why is it necessary to autoclave media along with magnetic stirer? Heat will affect it's property. moreover, not necessary to restire media after autoclaving.

  • Reply Daniel October 26, 2017 at 9:24 pm


  • Reply Merrick Kent January 2, 2018 at 7:23 pm

    Imagine what's in your tap drinking water

  • Reply Pon Murugan January 24, 2018 at 5:26 pm

    please video va Tamil ah podunga

  • Reply Muhammad Naseem February 11, 2018 at 8:18 pm


  • Reply Nandika Kaul February 19, 2018 at 5:45 pm

    This was so helpful. Thank you so much!

  • Reply Llew Gibson April 12, 2018 at 8:21 pm

    I seen your video mate, really love the content. Subbed straight away, We should connect!

  • Reply munde prakash April 28, 2018 at 4:11 pm

    Is agar compulsory could we prepare tissue culture at home??

  • Reply zyreneium May 11, 2018 at 7:59 am

    Hello! How many hours does it take to solidify?

  • Reply noopur kumari May 14, 2018 at 5:40 am


  • Reply Sindhu Konkapaka May 24, 2018 at 11:08 pm

    Has fiber ever been added as an ingredient when preparing agar media?

  • Reply HaydenHatTrick July 9, 2018 at 10:49 am

    In these comments, lots of people saying "ah, not the bench".
    I just light a bunsen burner and work within a half meter of it. A bunsen's convection current works really well for even a meter radius around it.

  • Reply نانا محمود July 13, 2018 at 4:20 pm

    Amazing 💕

  • Reply vitamin C July 17, 2018 at 3:17 am

    Hmm you open the petri dish wide open meaning cause of contamination. You should open it slightly just to add the agar to the petri dish

  • Reply mano Saparis September 23, 2018 at 12:57 pm


  • Reply wheretheavocadoesat xd October 22, 2018 at 4:37 am

    Kaway kaway mga taga sci tech dito :>

  • Reply saranya sakthivel October 25, 2018 at 3:00 pm

    it very useful to students

  • Reply saranya sakthivel October 25, 2018 at 3:00 pm

    tq so much

  • Reply جابر عبدربة November 22, 2018 at 5:53 pm


  • Reply Edward Santoro December 14, 2018 at 12:26 pm

    For how long can Agar-prepped petri dishes be stored?

  • Reply Mayank Vishesh February 21, 2019 at 8:38 pm

    It was helpful for biotechnology practical

  • Reply Icha Khofifah March 2, 2019 at 7:24 am

    Bukankah penuangan media tidak boleh dibuka terlalu lebar?

  • Reply Nandini Singh March 28, 2019 at 6:42 pm

    She's doing it in open environment, that might can cause contamination

  • Reply Tauseef Haider April 23, 2019 at 6:13 pm

    Anyone please tell me material required & process in proper written form. I have to solve my class work

  • Reply zin lee June 12, 2019 at 5:30 pm

    at last where did she store them n y using plastic bag

  • Reply Sourav Goswami June 21, 2019 at 3:36 am

    how do i know that how many plates are required for the pouring of agar?

  • Reply 陈彩玲 June 29, 2019 at 5:46 am

    Hello, competitive cost of fully automatic culture media production line with capacity of 6000 pcs per hour, if need more videos or information , please feel free to contact Ms Nancy +8613710656274(whatsapp)

  • Reply Ayush Gupta July 3, 2019 at 6:05 pm

    Agar media is costly …which other media can be used

  • Reply Justice Bernal August 25, 2019 at 2:29 am

    Wow, I just need to prepare some grub for me Tardigrades, this is a lot of work! The average Joe don't have no autoclave in his kitchen!

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