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Offlinemushroomnoob1981
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Registered: 06/15/15
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Endospores v. Autoclave/PC
    #22416975 - 10/22/15 06:53 AM (8 years, 3 months ago)

So as my name says, I am new to growing mushrooms (I've only been doing it about 5 months).  I have, however, spent 9 years working in biological and biochemical labs that use autoclaves.

I was wondering why there seems to be so much concern with respect to endospores surviving the PC process in a lot of the grain TEKs I've read because:

-Both a PC and an autoclave reach pressures / temperatures of 15 psi/ 121 °C

-Industrial autoclaves are routinely "validated" to ensure they produce sterility.  One of the tests is the biological indicator (BI) test.  This test involves placing highly heat-resistant bacterial endospores in the autoclave and then verifying that the spores have been killed.

http://www.cdc.gov/oralhealth/infectioncontrol/faq/sterilization_monitoring.htm

-If a PC and autoclave reach the same temp/pressure, and an autoclave is capable of killing highly heat-resistant endospores, shouldn't a PC be capable of killing endospores as well?


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Invisiblepaperbackwriter
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Registered: 03/31/14
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Re: Endospores v. Autoclave/PC [Re: mushroomnoob1981]
    #22417049 - 10/22/15 07:33 AM (8 years, 3 months ago)

I don't soak my grains, I leave pcd jars around for up to a week before inoculating, I use a PC.

I'm still something of a noob but I've yet to lose a jar that I couldn't attribute to a dirty LC or sloppy technique.


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Why should we strive with cynic frown
To knock their fairy castles down?  ~ Eliza Cook

It's rather embarrassing to have given one's entire life to pondering the human predicament and to find that in the end one has little more to say than, 'Try to be a little kinder.' ~Aldous Huxley


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Offlinespacechildo
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Re: Endospores v. Autoclave/PC [Re: mushroomnoob1981]
    #22417056 - 10/22/15 07:36 AM (8 years, 3 months ago)

15 psi for 90mins isnt enough to kill endospores it only knocks them back and give us a cpl weeks window to have mycelium colonize the grains.

aloha uses 60psi for their final run, not 100% sure but think they do it for 4-6 hrs or so.


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OfflineDrCrumbs
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Re: Endospores v. Autoclave/PC [Re: paperbackwriter]
    #22417059 - 10/22/15 07:38 AM (8 years, 3 months ago)

Is it that they think a PC wont kill them or is it that the concern is whether or not in a PC the internal temp of your target will reach 121C at certain length of time?


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InvisibleMunchauzen
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Re: Endospores v. Autoclave/PC [Re: mushroomnoob1981]
    #22417083 - 10/22/15 07:48 AM (8 years, 3 months ago)

Quote:

mushroomnoob1981 said:
So as my name says, I am new to growing mushrooms (I've only been doing it about 5 months).  I have, however, spent 9 years working in biological and biochemical labs that use autoclaves.

I was wondering why there seems to be so much concern with respect to endospores surviving the PC process in a lot of the grain TEKs I've read because:

-Both a PC and an autoclave reach pressures / temperatures of 15 psi/ 121 °C

-Industrial autoclaves are routinely "validated" to ensure they produce sterility.  One of the tests is the biological indicator (BI) test.  This test involves placing highly heat-resistant bacterial endospores in the autoclave and then verifying that the spores have been killed.

http://www.cdc.gov/oralhealth/infectioncontrol/faq/sterilization_monitoring.htm

-If a PC and autoclave reach the same temp/pressure, and an autoclave is capable of killing highly heat-resistant endospores, shouldn't a PC be capable of killing endospores as well?




a 2 hour cycle does not kill them, PC or autoclave. it damages them. they will recover and germinate in about 2 weeks time. it would take a 24+ hour cycle to completely destroy endospores. they didn't teach that in the lab?

A PC is fine. Very few people use autoclaves because they dump the pressure at the end of the cycle, instead of gradually cooling down. The pressure drop in an autoclave will make certain things, like a pre-poured agar petri dish, boil over. Basically anything with liquid in it will boil over from the autoclave's pressure drop.


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Offlineblackout
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Re: Endospores v. Autoclave/PC [Re: mushroomnoob1981]
    #22418773 - 10/22/15 03:17 PM (8 years, 3 months ago)

Quote:

mushroomnoob1981 said:
This test involves placing highly heat-resistant bacterial endospores in the autoclave and then verifying that the spores have been killed.



The test strip will be up to temperature very quickly. The grains in the centre of jars will not


http://www.fao.org/docrep/010/ai407e/ai407e22.htm

Those cans would probably have had liquid in them, which greatly aids heat transfer. Our grains are surrounded by air, a great insulator.


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OfflineKizzle
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Re: Endospores v. Autoclave/PC [Re: blackout]
    #22421012 - 10/22/15 11:53 PM (8 years, 3 months ago)

Yeah, got to remember there's a lot of air pockets in spawn jars and they act as an insulator. It's not a matter of PC vs autoclave. It's a matter of surface sterilization vs sterilization of grain. Fortunately the hardest to kill endospores require an anaerobic environment to grow so it's not necessary to kill all of them because there'll be plenty of oxygen being exchanged.


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Offlinemushpunx
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Re: Endospores v. Autoclave/PC [Re: Kizzle]
    #22421104 - 10/23/15 12:26 AM (8 years, 3 months ago)

Most of the contamination problems you encounter in this hobby will find thier way in during work with the lid off your jars , things like innoculations and grain to grain transfers.

Just use proper GE lids, PC for at least 90 min for jars quart size and under and 2-2.5 hours for things like spawn bags.


I just upgraded my PC to sterilizer tonight. Im rocking out at 28 PSI now ow ow!


--------------------

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