Australia's Science Forum

Dear All - I am having trouble with the peptone broth that did NOT become contaminated with microorganisms as expected during Pasteur's experiment. Must admit the peptone I am using has been in the lab for 25 years (That's how long I've been here) God knows how many years before that!! So maybe it's too old!! Just like I am feeling!!!! I used the usual recipe i.e. 5 teaspoons of peptone dissolved in 100ml of hot water and then diluted to 1 litre. from the Clearway Science Teacher's Resource Book. then 50ml into a conical flask- one open and one fitted with a coiled tube and boiled gently for 5 minutes. Is this the recipe most of you use?? If not, would you mind telling me what recipe you do use, your assistance would be greatly appreciated. Cheers Judy.

Hi Judy,

Have a look at HSC Online, i.e. http://hsc.csu.edu.au/biology/core/bett ... 43net.html.
This suggests using meat extract cubes. You can buy these from a supermarket considerably fresher than the peptone you have. Our peptone is a similar vintage to yours. It predates me and I have been here a similar time to you - 27 years.

When making up protein solutions for food tests I always used peptone but after a short time it stank! I changed to using granulated gelatin as the protein source and it works well and is much more pleasant to the nose.

Robbie

Dear Robbie - Thank you very much for your help re the peptone broth
and also the protein solutions, I too have the same problem - so I will be changing to the gelatin solution as suggested. Once again thanks a lot!! Cheers Judy.