How much agar for petri dish

Log in Register. Log in. Create an Account First Name:. Last Name:. Confirm Password. I am a teacher. Sign me up for the newsletter. Why should I sign up? Reset Password Email:. Tip: Microbiologists typically use sterile, disposable polystyrene plates, but you can also use glass Petri dishes or even baby food jars.

If you use glass dishes or jars, you may find it easier to sterilize the culture media directly in them. Prepare the media as in Step 3, but instead of sterilizing it, boil it until the agar is dissolved, then pour into individual containers. Sterilize the media in the containers in an autoclave or pressure cooker.

Choose a recipe Choose a recipe from the Media Recipes page or use one of your own. Gather supplies. Media Recipe ingredients see the Media Recipes page sterile, polystyrene Petri dishes. Prepare media. Assemble the ingredients according to the recipe of your choice. Pour ml of hot agar into each petri dish, just covering the bottom. Replace the dish top immediately after pouring to prevent contamination. Let dishes stand for 1 hour, allowing agar to solidify.

Note: This agar can be sterilized in a pressure cooker before pouring into the sterile plastic dishes. Use 15 lb. This agar does not have nutrients added to it; however, since it's an organic substance made from seaweed , it's a medium that encourages bacteria growth. You can mix a little chicken broth with the agar if you want to add more nutrients! Learn More. What is this? We want this item to be alive when you get it! Therefore, we need to know when you'll be home to receive it minimizing the package's exposure to the elements.

Interesting, but useless. This allows space for bubbles to rise while the agar is melting in the microwave and saves you cleaning up overflowing agar from the microwave! Autoclave your medium for 25 minutes. After autoclaving, you can of course store the medium-agar mix in a toughened glass bottle then melt it in a microwave or water bath when needed. Make sure you use toughened glass bottles, or disaster see 2 can strike. Remember to use heat resistant gloves when handling hot medium straight out of the autoclave.

Using the water bath when making agar plates means you can consistently cool the mixture to just above the solidification temperature. Before I used a water bath, I used to just cool it in the air, but would inevitably forget about it and come back to find solidification had already started — lumpy plates are no good for spreading! You can now add any antibiotics or supplements, and be confident that the agar is at a suitable temperature because you have cooled it in the water bath.

Use about 30 mL of the agar-medium mix to create each plate when using mm diameter dishes. The less agar-medium mix in each plate, the more easily they will dry out. Suck up 2—3 mL more than you need to minimize blowing bubbles into the plate. Use an open flame e. If there are any bubbles in the plates, briefly pass the flame over to pop them.

Just leave them alone and maybe admire your perfect agar plates while you wait! Drying the plate is very important for storing the plates and growing colonies on them.