Australia's Science Forum

Shell1 I was interested in the Agar you recommended as it is much cheaper than what we buy from Sigma. Do you mind telling me what you grow on your agar plates. It may be suitable for us and save us a lot of money.

How much agar-agar per 100ml does it take to set it. I have a prac for 1.5% agar-agar and I don't think it will be strong enough.

Off the top of my head, I think it's about 15g per litre of water, so not sure what you'll end up with only 1.5%.

And David, going back to your post from October (which I had missed), the recipe Shell has given you will make something similar to nutrient agar, so broad use. Without the agar, it also makes a great nutrient broth. Yes, it is cheaper, but is a bit more time consuming, so you need to weigh up your material costs against the time it will take to make. When I was making a lot of plates, and had the time, I would use this recipe for the junior classes, and save the purchased nutrient agar for the seniors - although they both worked pretty well.

Oh, so wrong - 28g per litre is the amount for the nutrient agar I have.

I have bumped this to the top, as there are some great reads, regarding making agar for us all

I made agar plates with a student using the recipe on science assist

agar, beef stock and peptone

there was no mention of the NaCl in the recipe above


are these going to work? I'd hate her project to not have any results

thank you for any help

I've always added NaCl myself, however, I wouldn't doubt the information on Scienceassist so you should be right. Commercial stock is pretty salty.
Could you inoculate and incubate one over the weekend as a test?

This is a recipe that I got from one of the SWS Network meetings, it works all the time.
500 mL water
10 g Agar (I use 'Labchem' Agar, powder, from Ajax, one bottle of 500g lasts me a long time).
1.5 g Beef stock cube/ powder (I use Bonox, conc. beef stock, about a third of a teaspoon)
2.5g peptone
Makes approximately 15 plates,
I hope this helps,
Ines

Question for the brains trust.

I have an Extension science student using the following agar, Murashige and Skoog Shoot Multiplication Medium A. used for plant tissue culture. However it is also growing other bacteria and mould. My BRAIN "DO NOT OPEN" plates. Teacher saying she needs to open to place on slide under microscope.

What happen in the DET schools when Contaminated plates are opened by mistake or on purpose.

Thanks in advance.

thank you both for the reply
Merilyn1 I did exactly that but I took it home because I wouldn't be in for a few days now I cant remember the nice warm spot I put it in ohmy
Thank you Ines thats pretty much what she used so fingers crossed.

I’m with you. Generally year 12s can open their agar plates of they know what they’re culturing and there aren’t any unknowns. But since there unknowns on that plate I’d also be advising against it!! Can’t they look at them through the plates?

mikah wrote: ↑02 Jul 2019, 10:56 thank you both for the reply
Merilyn1 I did exactly that but I took it home because I wouldn't be in for a few days now I cant remember the nice warm spot I put it in ohmy
Thank you Ines thats pretty much what she used so fingers crossed.

Oops!

My personal opinion is never, ever open the plates. You cannot be sure what is growing in there. You could be exposing yourself to millions of particles of a pathogen, with terrible and possibly life-changing consequences.

If you are looking for Agar / microbiology supplies try Amyl media.

I have been using their products for over 20 years.

Agar is much cheaper than other suppliers.

Amyl Media Pty Ltd

39 Healey Rd,
Dandenong Vic 3175
PO Box 4129,
Dandenong South, Vic 3164
Australia

Hi Brains Trust

I've been asked by a teacher for a students SRP to make up 20 agar plates but 5 different ways.
So for each 4 plates:
x4 plain
x4 glucose
x4 saccharine
x4 Acesulfame
x4 Sucralose

They want the sugars to be made up in the agar as it sterilises so its all distributed evenly when it comes to pouring them.
Has anyone ever done this before and know if these sweeteners can be purchased from a supplier?

Hope this makes sense,
Thanks

HI,
Saccharine goes by the names of - Sweet & Low, Sweet Twin, Necta Sweet.
Sucralose goes by the name of Splenda. I saw the Splenda product in Woolworths today in the sugar section. That is the artificial sugar/sweetener section.
Acesulfame - E950, Sweet One, Sunetti.
I think you will have to do some research on the internet to track these items down.
Should be able to buy glucose from Woolies or Coles.
Sorry I can't help you any further.

Try here for the acesulfame potassium
https://www.melbournefooddepot.com/buy/ ... -200g/ACEK