Re: if nutrient agar gets hard in the bottle can i get it to is original state

Date: Sun Feb 18 13:47:19 2001
Posted By: Lynn Bry, MD/PhD, Department of Pathology, Brigham & Women's Hospital, Harvard Medical School
Area of science: Microbiology
ID: 982516443.Mi

Message:

Hi Allison -

In fact, there is a very easy way to re-liquefy your agar, so fear not!

We do this frequently in the lab, as it is common practice to make a batch of agar media, pour it into glass bottles, let it solidify, then heat the agar when needed to pour Petrie plates.

You'll need the following:

Glass bowl or microwave-safe bowl in which you can place the bottle.
Water, to go into the bowl.
Microwave oven that can hold the bottle + bowl.
Oven mitt or potholders for removing the bottle after it has warmed (it will be quite hot!).
Have an adult help you with the reheating. The agar and heated water will easily burn your skin if not handled properly.

Pour some water into the bowl and stand your bottle + agar upright in the middle. Don't put the water in the bottle, only in the bowl. Ideally, you'd like the water to come to about the level of the solidified media. We generally use a large glass beaker to hold the bottle, but you can use a bowl if you don't have a beaker available. The point of heating the agar in this manner is to do it slowly so you don't overheat, and potentially burn, the media.

Loosen the cap on the bottle so the heat and steam can escape as the bottle is being heated. It is very impotant that you loosen the cap, else you could have a mini-explosion if you open the bottle after it has been heated (not good!). Place everything in the microwave oven. Start it on high heat for ~2 minutes. Chances are the agar will not have melted by this time, but you can watch it to make certain nothing is boiling over and making a mess in your oven. Repeat as often as needed until the agar has completely liquefied.

With oven mitts, carefully remove the bowl + melted agar. Be careful when handling the hot agar as it will burn your skin if you spill it. Pour your plates, or otherwise distribute the media as needed.

Hope this helps..

-L. Bry, MadSci Admin

p.s. this also works for melting jello!

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