Agar Preparation without a Pressure Cooker

Date: June 15 2022

Goal

The goal of the experiment is to determine whether a pressure cooker is necessary to sterilize agar.  Have a look at the experiment on my YouTube Channel 

Materials Required

  • Agar powder 5 g
  • Light Malt Extra 10g
  • Boiling water 300 ml
  • Food coloring (optional)
  • Cup
  • Glass Petri dishes
  • Glass bottle
  • Micropore tap
  • Aluminum foil
  • Rubber bands
  • Empty glass jars
  • Big pot
  • Still Air box (SAB)
  • Towel (dunked in hot water and dish washing liquid)
  • Paper towels
  • Rubbing alcohol
  • Oven tray
  • Parafilm

Method

  1. Pre heat oven to 150 degrees Celsius (300 Fahrenheit)
  2. Clean out petri dishes with rubbing alcohol and paper towel
  3. Roll up the petri dishes in the aluminum foil and fold the edges closed
  4. Place them in a baking tray and put them in the oven for 20 minutes
  5. Add 5 grams of Agar Powder into a cup
  6. Put 10 grams of light malt extract into the cup
  7. Add 300 ml of boiling water.
  8. Stir and add food coloring if desired
  9. Pour into glass bottle.
  10. Pierce glass bottle cap with a knife
  11. Cover the opening of the bottle cap with micro pour tap
  12. Place cap on bottle and tighten it.
  13. Put aluminum foil over the bottle cap and secure with a rubber band
  14. Put big pot on stove and place two paper towels in the pot
  15. Place agar bottle in a pot with glass jars (the jars keep the bottle for tipping and spilling out agar)
  16. Fill the pot up half way with water.
  17. Steam bath the agar for 90 minutes
  18. Place towel on a table
  19. Place still air box on towel
  20. Put petri dishes in still air box
  21. Place agar bottle in still air box
  22. Wipe down agar bottle with a paper towel and rubbing alcohol
  23. Remove aluminum foil from agar bottle and petri dishes
  24. Stack the petri dishes (I do 5 because my finger dexterity sucks)
  25. Lift the lid of petri dish and pour in agar
  26. Place lid on petri dish and lift lid from petri dish below.
  27. Continue until the stack is complete
  28. Leave the agar to set.
  29. Seal petri dishes with parafilm or inoculate with spores.

Observations and Results

Observations 

The agar bottle might be fucking hot so be careful of your fingers

The method for pouring and staking is the best because you can avoid condensation and you won’t tip out the agar when you move the petri dishes.

Do not leave the petri dishes in the still air box for more than a day.

Take your time with the pour because you will mess (talking from personal experience)

The parafilm might be a bit tricky to pull. Make sure the other petri dishes are out of the way when you add the parafilm or you might knock over your stacks and then it is useless.  (I knocked over the petri dishes)

Shake the liquid culture syringes properly.

Results 

The results were subpar. I did leave the agar plate in the still air box for three days after I poured them. I got busy and was unable to inoculate them.

I think that I did not shake the liquid culture syringe enough because I did not see much mycelium growth for some of the petri dishes.

I have noticed slim mold growing and one petri dish has some cobweb mold.

Conclusion

My method of pouring and inoculating was subpar because I haven’t done agar work in a while

I had more contaminations than normal and that could be because of

  • Knocking over the petri dishes when adding the parafilm
  • Leaving the petri dishes (without parafilm) in the still air box for 3 days
  • Not shaking the liquid culture syringe properly

Reference and Supply list

MEA Agar recipe:

Masiye labs 

  • Glass petri dishes

Woolworths food

  • Glass bottle for agar

Takealot.com 

  • Light malt extract
  • Glass jars

Sporespot.com

  • Liquid culture syringe
  • Agar powder
  • Parafilm
  • Still air box (you can make your own as well)