Australia's Science Forum

Hi Everyone,
I have just gone to make some agar plates and discovered the peptone has become rock hard.
Is it essential or can I replace it with something? I won't have time to buy it as i need the plates for Wednesday.
Any suggestions?
Helen

It will still work. Just have to scrape some with a spoon. Don't suppose you have nutrient agar, then you don't need the peptone, and it is really easy to use.

To prepare nutrient agar you can use 10g of beef stock cubes and Marmite, in place of beef extract and peptone.
The rest is identical.
Lada
PS I buy nutrient agar already in powder form. Just dissolve and autoclave.

Please do a search on agar plates, I believe some one used Gelatine, and if I remember correctly, it worked out fine.

I changed to using gelatine instead of peptone some time ago. It works well, is cheaper and much easier to obtain. Just use the same amount of gelatine as you would use peptone.

Cheers,

Robbie

I use beef stock powder if I don't have any peptone. If you're making 1L of agar use 3g of stock powder. This works well.
Your food tech department may have some if you don't.

Lorrae

I use Bonox and it works fine
Noona

Also check the posts in 'Peptone vs Pepsin' in recipes and pracs.

Cheers
Fran

Thanks everyone,
I have some beef stock cubes and some gelatin so will give it a go with one of those.
Helen