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sawdust

Registered: 02/05/11
Posts: 61
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agar agar
#22056060 - 08/06/15 11:07 PM (8 years, 5 months ago) |
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I have noticed fungi.com agar is thick at hot temperature on a stir plate using 10 grams/500ml even after a long time.
but I have lab agar that is very thin like water once it fully dissolves using the same ratios The liquid also becomes very clear and the agar is not visible at all. However, when fist adding agar it sticks together a little until it dissolves. Fungi.com dissolves better in cold water.
I have used one half the amount of Malt extract agar recommend by fungi.com on the bottle with completely solid media once sterilized and poured into petri plates.
When I first used fungi.com agar I had boil over problems until I raised the amount of water in the pressure cooker and cut their recommendation in half. With the "lab agar" boil over never occurred except by accident when bringing to a boil to fast on a hot/stir plate.
The mesh size appears the same. Fungi.com agar dissolves fast(non chunks) but remains thick even after boiling. Its like sterilization alters the substance in a way boiling cannot achieve. Because it is very much liquid like water when removing from the pressure cooker.
Does anyone know the reason for this?
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Chk
Reverser


Registered: 09/06/13
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Re: agar agar [Re: sawdust]
#22056948 - 08/07/15 07:49 AM (8 years, 5 months ago) |
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All agar is not made equal, you need more or less depending on the brand
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matsc
Stranger



Registered: 09/17/12
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Re: agar agar [Re: Chk]
#22058637 - 08/07/15 01:11 PM (8 years, 5 months ago) |
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Agar will form a "solid" anywhere from about 1% up. Even 0.7% is fairly solid, if a bit on the jiggly side. As you're using a pre-mix I can't tell what the composition is, but the recipe is likely something in that range. If you mean you're just using straight 2% agar, then yes it will be rather syrupy. It sets up tougher and is more resistant to gouging/tearing, but god is it annoying to work with.
The agar I work with in lab is a tawny/beige granular material, that tends to dissolve clear but a bit tinted. We also have agarose, which is a much finer granulated material that is white/colorless with a much more tightly defined melting point.
(Agar is a mixture of various polysaccharides, including agarose. For media purposes this is perfectly acceptable, and its only for things like gel electrophoresis where you need the highly refined stuff).
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sawdust

Registered: 02/05/11
Posts: 61
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Re: agar agar [Re: matsc]
#22059018 - 08/07/15 02:46 PM (8 years, 5 months ago) |
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10 grams of fungi perfecti agar will solidly 1,300ml of water into a very solid gel upon cooling to room temperature!!! Experimental fact.
Why do they recommend 10 grams per 500ml?
They are recommending 3 times the amount of agar required to from a good solid agar medium.
Agar composition get complicated, but using 3 times the amount needed seems wasteful of a known agar.
Also, by using too much agar filling slants is more messy. It is easier to pour hot water than honey.
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ashfiken
TotalCrazyasshole


Registered: 09/06/06
Posts: 3,073
Loc: SCranton
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Re: agar agar [Re: sawdust]
#22059227 - 08/07/15 03:31 PM (8 years, 5 months ago) |
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Simple fact, using 3x of their agar than what you need,, Sells them more agar 
Cheers
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drake89
Mushroom Magnate



Registered: 06/26/11
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Quote:
ashfiken said: Simple fact, using 3x of their agar than what you need,, Sells them more agar 
Cheers
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matsc
Stranger



Registered: 09/17/12
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Re: agar agar [Re: drake89]
#22060433 - 08/07/15 08:20 PM (8 years, 5 months ago) |
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It also affects things such as speed of hyphal spread and penetration rates... but outside of a lab those really arent all that relevant. They probably just went with 2% because its a common, if somewhat high, number to use.
And yeah, business.
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ashfiken
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Re: agar agar [Re: matsc]
#22062163 - 08/08/15 10:28 AM (8 years, 5 months ago) |
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Very true, when it comes down to labwork, id assume the exact amount of agar\media\food for the myc to grow on can be just as big of a variable as what kind its given, or at least a aignificant factor that would certainly change the things you mentioned, agar mix to agar mix. Ie If the myc is given Exactly what it needs vs. Any other instance it will perform better, differently, more vigorously, whatever. Good thinking, hadn't gone that into it my damn self, good thing to do though.
Cheers
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god2hateyou
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Registered: 08/07/15
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neat,
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