Table of Contents
How do you dispose of Petri dishes with bacteria?
You can do this with just regular bleach. Give it a swirl in the dishes, making sure it’s hitting all the surfaces, and dump it. Be careful not to get the bleach on your skin or eyes! Wear protection if necessary!
Why must the molten agar be cooled before pouring the plates?
Why should agar be cooled to 45 degree celcus before pouring? To reduce condensation and to provide easier handling of liquid medium. produces color changes in response to differences in reactions by bacteria such as differences in fermentation of sugars; contains fermentable sugars or other differential agents.
How do you prevent an agar solidify before pour it out?
Store plates upside down in a refrigerator or cold room. If they are stored in a room, check the plates after a few hours for condensation in the lid. If you have the plates upside down and there is condensation in the lid, there must be some heat source above that is driving water out of the agar and into the lid.
How do you aseptically pour an agar plate?
For sterilization, freshly mixed agar is poured into loosely capped bottles and placed in anautoclave, where high temperatures and pressure are used to kill microbes currently in the agar. After the agar is sterilized, it is stored in a warming oven, so that it remains liquid, and ready for use.
Can agar go down the drain?
Never pour concentrated agar or agarose solutions down the drain. They will solidified and clog the drain.
How do you dispose of unused agar plates?
Dispose of unused plain agar in plastic plates directly into a trash can. Agar with any additives are biohazards and should be sterilized before disposal. Scrape unused agar out of glass petri dishes and throw it away.
How do you store unused agar plates?
Store agar plates in a refrigerator. Most bacteria cannot grow well in cold temperatures. Store plates in a cold room if a refrigerator is not available. If you are storing plates in a cold room, check the plates for condensation a few hours after pouring.
How do you remove condensation from agar plates?
Another commonly practiced technique is to take a jar, something wider than your petri dish and fill it with hot water and once you’ve poured your stack of dishes, put the jar of hot water on the top dish and leave it all to cool.
How do you solidify agar?
Cool the medium-agar mix to 55°C. For routinely consistent results, do the cooling for a couple of hours in a 55°C water bath. Agar starts to solidify at about 50°C. Using the water bath when making agar plates means you can consistently cool the mixture to just above the solidification temperature.
Why is my agar agar not solidifying?
If there are still grainy bits of agar floating or sticking to the bottom of the pan, the jelly will not set properly. Never mix agar powder with warm/hot water as it will clump and become impossible to dissolve. Stir into room temperature liquid and then bring it to a rolling boil, making sure the agar has dissolved.
Why do you place agar plates upside down?
Petri dishes need to be incubated upside-down to lessen contamination risks from airborne particles landing on them and to prevent the accumulation of water condensation that could disturb or compromise a culture.
What happens if agar is too hot?
If the agar is too hot, the bacteria in the sample may be killed. If the agar is too cool, the medium may be lumpy once solidified.
What’s the best way to store molten agar?
The instructions are for right-handed workers – turn them around if you are left-handed! 1 Use a water bath at 50 °C to store bottles of molten agar. 2 Use plates as soon as possible after pouring. Store in sealed plastic bags to prevent the agar from drying out if they are not going to be used straight away.
Do you have to cover the base of an agar plate?
The base of the plate must be covered, agar must not touch the lid of the plate, and the surface must be smooth with no bubbles. If there are bubbles, you can try flaming the agar surface very briefly to disperse them – but this carries the risk of melting the Petri dish! h Allow the plate to solidify ( Note 1 ).
How do you transfer culture from agar to broth?
To transfer a culture from an agar plate to a broth or agar slant: Place the Bunsen burner in front of you and assemble all necessary equipment with in arms reach. Position everything so that you will not burn yourself while trying to inoculate your tubes. Label the tube of broth or agar to be inoculated with identifying marks.
How to pour Agar into a petri dish?
Unscrew the bottle by turning with your right hand. Leave the cap gripped by the little finger of the left hand. d Flame the neck of the bottle. e Lift the lid of the Petri dish slightly with your left hand and pour the sterile molten agar into the Petri dish.