Protocol Online logo
Top : New Forum Archives (2009-): : General Lab Techniques

spread bacteria on agar plate until it is dry? - or if it is still wet is ok? (a very basic question) (Feb/21/2010 )

Hi,

when you spread liquid transformed bacteria on agar plate by L-shpaed glass rod, do you spread it until the plate is completely dry? or we need to keep it a little wet so that not all the bacteria break during spreading?

thanks

-Curtis-

Curtis on Feb 21 2010, 08:23 AM said:

Hi,

when you spread liquid transformed bacteria on agar plate by L-shpaed glass rod, do you spread it until the plate is completely dry? or we need to keep it a little wet so that not all the bacteria break during spreading?

thanks



I don't spin until dry. Sometimes the volume is low enough that it dries pretty quickly, but that depends on how dry the plate is, too. If I spread more than 100 or 150 ul, it's rarely dry. I let it sit on the bench until it dries completely, or put it in the incubator cell-side up until it's dry, then flip it over to incubate.

-fishdoc-

I agree with fishdoc.

The point or idea is to spread the bacteria, and by spinning a few times or moving the spatula you will do that.
No need to keep turning until its dry, you do more harm then good that way.

-pito-

most bacteria wont break when spreading until dry.
Basically it is importrant to get a dry surface of your agar plate, because otherwise the bacteria will "flow" in the remanant water and you will get one big blob of colony and not many single ones. you can get a dry surface by spreading the liquid until it the plate is dry (which is easy if you "dry" your plates o/n at 37C, even for 100/150L) or you can do like my previous posters recommended.

-gebirgsziege-