trish armstrong wrote:
Anyway was thinking can we substitute gelatine or something for plates for junior classes?????
For cost saving.
Or if anyone knows how to buy agar powder cheap.Let us know your secret
Trish.
ps. just searched google and some mention guar gum or xanthan gum any one tried these substitutes??????
Hi Trish,
if you want a cheap way to grow basic bacteria etc for junior classes, you can use the humble old potato :
Potato as an alternative culture medium for fungus and bacteria.
Peel a large potato and cut into 6mm thick slices.
Place potato slices in boiling water and boil for 1 minute.
Use sterilised tweezers to transfer each slice to a sterile petri dish and allow to cool.
Inoculate the same way as for agar plates.
Potato is particularly good for culturing microbes from soil.
I know what you mean re the cost of agar & how time consuming it is too......I make up several hundred at a time because we have 5 year 11 biology classes + 2 year 11 IB classes - at least it keeps me off the streets
Currently I've also got 5 year 12 IB kids doing micro pracs but for them we bought Petrifilm plates - brilliant things ($$$ but worth it for the results & quality of data they get)
Dear All - Just wondering how you cut the blocks of agar into the 1,2,3cm cubes. I always have trouble using a knife and ruler, I find the knife seems to skid off to one side in the jelly-like substance and I can never get a reasonably accurate square. I was trying to talk one of the maintenance fellows into making me something akin to a cheese/butter cutter so I could cut them accurately in one fell swoop, but no success so far. What do others do? I would be interested to know. Cheers. Judy
If you have trouble cutting agar blocks straight, buy one of thoes cheese cutters like a gillotine with a fine wire as the cutter or ask your TAS section for a bench hook to have on permanent loan the bench hook is a flat board with a a piece on top and bottom at oppsite ends for cutting wood with a tennon saw the bit that sticks up you use as a guide
Hope that's clear