Agar doesn't set

[Eric Carbobiach]

Hello, friends!

I'm having problems with agar. Here in Brazil, lab grade is too expensive, so i'm using food grade, from health store.

But only became gel, doesnt firm enought to use the loop. So i tried another store. Same problem. Tried more concentrated, without success.

My procedure:

I prepare a media with 3% DME, 0,02% yeast extract and 2% agar (i tried with 4% and 8% but still only a gel).
First i make a wort (for starter), while let agar hydratates. When its done, i start to heat to dissolve agar and add a little bit of the wort with a pipete, to get 3%.
After that, i fill the falcon tubes and petri dishes and autoclave. I wait get cold and set, what is not happening.

I've tried to use only agar and water. Same thing.

Can anyone point some incorrect procedure or probably ive got bad agar from the same supplier?

Thanks! Cheers!

 

[RPh_Guy]

What are the ingredients in the "agar"? Is it actually agar or gelatin?

If you turn the plate upside-down after it cools, does it stay in place?

The DME and agar should be measured by dry weight; you should not need a pipette.

 

[Eric Carbobiach]

What are the ingredients in the "agar"? Is it actually agar or gelatin?

If you turn the plate upside-down after it cools, does it stay in place?

The DME and agar should be measured by dry weight; you should not need a pipette.

Hello, friend! I use a pipette because I'm using a little part of wort from a starter.

And about the agar, it doesn't stay in place. It just got a consistence of somewhat like baby food.

Some posts say about pH. But, can pH be a problem here, with that ingredients?

I've bought another one agar. I'll try again.

 

[RPh_Guy]

Sounds like some kind of problem with whatever agar product you had.
It should set with 2-4% agar.

 

[slickfish]

Agar needs to boil to fully gelatinize.

 

[RPh_Guy]

Agar needs to boil to fully gelatinize.

Good point. I figured it was probably boiled long enough when he "autoclaved" it, but maybe not.

i fill the falcon tubes and petri dishes and autoclave

 

[slickfish]

I missed that part. Auto leaving should have done it.

 

[Eric Carbobiach]

Sounds like some kind of problem with whatever agar product you had.
It should set with 2-4% agar.

I missed that part. Auto leaving should have done it.

Yeah, probably is the agar with poor quality. I'll try this one and if don't work, I'll buy by internet a lab grade one. Thanks, guys! Cheers!

 

[Eric Carbobiach]

UPDATE

Yeah, was just a very bad agar. Using this one, I've got better results and I could use the loop very well!

Thanks, people!