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Sterilize substrate better than pastuerize?
    #2392917 -

I have a rather large PC and am thinking it might be worth my time to sterilize my substrate. I'll be using sterile media when I innoculate, I'm thinking I might be better off to keep it all as sterile as possible throughout everything.

Any thoughts on this?

Thanks


--------------------
From The sacred clan of the Indol Ring enters the
Claviceps Purpurea fungi to enlighten all seekers of truth.


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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2393011 -

It is generally accepted that pasteurized substrates are more resistant to contamination. If you do work with sterile substrate you will have to work in a sterile environment. Unless you are like me, I use sterilized substrate in an open environment, but with the proper application of a peroxide solution to prevent germination of contaminants.

You'll be walking a narrow path if you use sterilized substrates. Check your balance.

Joshua


--------------------
The Shroomery Bookstore

Great books for inquiring minds!

"Life After Death is Saprophytic!"

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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2393017 -

Cool and twisted avatar!

Joshua


--------------------
The Shroomery Bookstore

Great books for inquiring minds!

"Life After Death is Saprophytic!"

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Re: Sterilize substrate better than pastuerize? [Re: Joshua]
    #2394461 -

Joshua said:
It is generally accepted that pasteurized substrates are more resistant to contamination. If you do work with sterile substrate you will have to work in a sterile environment. Unless you are like me, I use sterilized substrate in an open environment, but with the proper application of a peroxide solution to prevent germination of contaminants.
.
You'll be walking a narrow path if you use sterilized substrates. Check your balance.

Joshua


Hi Joshua,


So you're saying that pastuerized gets less contaminated than sterile substrates? That doesn't make sense to me. I've read others say pastuerization is better for substrate than sterilization so that's why I'm asking here.

Help me understand. Here's what makes sense to me:

If you sterilize something you kill all the bacteria & fungus in the substrate. If you pastuerize something you're killing off the most easily killed bacteria but leaving some behind.

I remember from micro class that when bacteria & yeast/fungi compete for the same source, the one with the better foothold survives. If you kill off all the bacteria, the fungi you innoculate into the substrate have a great head start on any contamination that happens afterward. The longer the fungi overtakes the substrate, the harder for bacteria to get in there & contaminate.

I Understand for soil to be useful for outdoor crops there has to be bacteria for nitrogen fixing but that's for continued replenishment of the soil (a'la nitrogen fixing bacteria). In growing mushrooms, the nutrients in the substrate are depleted and the substrate is not reused after the grow is over.

I understand if there's a presence of bacteria working against the fungi, the surviving fungi will be stronger and they will survive better in the wild but it isn't wild fungi I'm talking about.

So why is pastuerization better to use with a substrate before casing than sterilized?

BTW, Thanks for the mention of my avitar, it looks better with a bigger picture. When they painted the double lines, they didn't care what was on the road, Wasn't their job to move anything, just paint.


--------------------
From The sacred clan of the Indol Ring enters the
Claviceps Purpurea fungi to enlighten all seekers of truth.


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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2394496 -

Sterilized substrate contaminates quickly because the new organisms have no competitors there. Mushrooms seem to do well against organisms that remain after pasteurization because they thrive at a different temperatures then those who survived the high temp pasteurization.
Of course if you can keep it sterile then sterilized substrate should work better.

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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2394507 -

This is the explanation in the FAQ.

http://www.shroomery.org/index/par/23371



When pasteurization occurs, bacteria that thrive in higher temps are left. These bacteria grow more slowly at incubation temps than the mycelium, which means the mycelium wins out easily. These same bacteria excrete bacterial growth inhibitors to keep contaminant bacteria in check, and to a lesser degree fungi. Because the fungi you spawn with has such a huge foothold in comparison, the inhibitors do not affect the fungi of choice.

There is a bevergage called kefir in which milk is fermented by up to one hundred different organisms, most of which are bacteria. Some of these bacteria are even considered pathogenic. However in the context of the kefir microsociety all of the bacteria are co-regulated and kept in a very nice balance so that no one species wins out. All of the bacteria get along and the mixture can be ingested.

Anyway, I believe that the success of pasteurization is dependant on the local balance of bacteria and fungi. It is possible that the local population has a species that does not die durring pasteurization and can grow at a high rate in incubation temps. To adjust, first of all make sure your pasteurization technique is proper. The middle of the substrate should be heated to a minimal temp for a specific time. Pasteurization can be carried out at varying levels. For example, Stamets in TMC suggests steam pasteurization at 140 F for 2 hours. I use water immersion at 175 F for 1-1.5 hours. If you are obtaining poor results with pasteurization, go ahead and try sterilization, but keep in mind that the substrate will need to be cared for even more carefully than with pasteurized substrate.

At least that is how I understand it.

Joshua


--------------------
The Shroomery Bookstore

Great books for inquiring minds!

"Life After Death is Saprophytic!"

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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2396536 -

Thank you all!

It makes sense.

I was planning on doing everything in as sterile an environment as possible so that I could break up the spawn into a sterile substrate & then case with sterile vermiculite. I suppose it doesn't matter once the lower temp bacteria are killed & the higher temp bacteria remain to do their thing & keep away other bacteria.

Many thanks for the pointers


--------------------
From The sacred clan of the Indol Ring enters the
Claviceps Purpurea fungi to enlighten all seekers of truth.


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Re: Sterilize substrate better than pastuerize? [Re: megalomando]
    #2403752 -

If your pc is truly large, then sterilize that shit!!!

the thing is, dung/compost is not all that contaminable to begin with. most of the brilliant greens and oranges are fond of growing on DEAD MYCELIA. if you mishandle your casing, and the green manifests, it is not always a matter of the substrate being improperly sterile or pasteurized.

That being said, sterilization is better than pasteurization, IMO. try this, allow some substrate from both procedures to contaminate in the open air in your house. i think you will be surprised.

Use the pillow case, keep it closed, spray peroxide and water solution anytime the substrate is exposed, mix your grain spawn into the substrate via the pillow, pour from the pillow into the prepared container of your choice/dogma/creed.

I THINK A GREAT MANY FAILURES OF PASTEURIZATION, HOWEVER, ARE MORE CLOSELY LINKED TO WATER CONTENT THAN ANYTHING ELSE.

if your substrate is too wet at spawning, even slightly, your chance of contamination is increased exponentially. pasteurization lends itself to overly wet substrates.

pc your compost up off of the bottom of your pc. let steam escape. don't soak you substrate - if it is open and airy, it will be more likely to come out sterile. no draining necessary if the water content is right to begin with......

peas


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You do not know me.

You can't see me.

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