Ask A Scientist Molecular Biology Archive

name         Kim
status       other
age          30s

How do you make homemade agar?
------------------------------------------------
HI
You should be able to make your own media at home.  Make sure that you keep
the petri dishes in their covering until just before you use them or they
can become contaminated.  You are right, the bouillon cubes won't "melt".
You can get some Knox brand gelatin from the store and make it kind of like
you would make jello for Finger Jell-O other words you want it a little
stiffer than normal.  Follow the directions on the package but add perhaps a
little less water.  Once you have boiled the water and added the gelatin, add
some beef bouillon to it and dissolve it.  This give the nutrients that the
bacteria need.  Keep in mind, that this may not completely sterilize the
media-there are bacteria that can survive boiling temperatures.  Pour a
little into a petri dish and let it solidify.  This may take some trial and
error to get it the consistency that you want.  I am also thinking that if
you are testing the effect of boiling the water you may want to add a little
of your specimen directly to the agar before it solidifies.  Then any
colonies which might be in the water specimen will be mixed directly in with
the agar.  You would then count the colonies after incubating.  You can
incubate them at room temperature for 48-72 hours.  Since you are not
completely sterilizing the agar itself you may be confused by any colonies
that grow-do they come from the agar itself or from the boiled water?  Unless
you can autoclave your media, it will be difficult to completely sterilize
your media.

vanhoeck
=========================================================