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Microbe Heat Resistance

  1. Oct 18, 2005 #1


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    Does anyone know of a good reference for heat resistance of microbes? What would really help would be any listing of decimal reduction times (D-values) at a given process temperature and z values. I'm just trying to make sure our autoclave kills everything it's supposed to for someone, so I've got a list of microbes with initial # of colony forming units from some bioburden studies. If anyone can point me towards a good reference, that would be a big help. Thanks.
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  3. Oct 18, 2005 #2


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    Autoclave doesnt kill certain archaebacteria

    Edit: Ok I dug up some info for you:

    Also there are pH-tolerant archaebacteria that grow in highly acidic (pH=0.7) and highly basic (ph=11) environments.

    And then there are pressure-tolerant archaebacteria that have been isolated from ocean depths and requiring pressures of 300 atm just to survive, and tolerating up to 800 atm.
    Last edited: Oct 18, 2005
  4. Oct 19, 2005 #3


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    In terms of practical use of autoclaving for the destruction of your typical contaminating species I would guess that the standard protocols remove 99%+ of the bacteria on your surfaces. Unless you, or your colleagues, are directly working with them, the chances of you running into any of the extreme-environment tolerant species is minimal.
    If you are looking for some sort of laboratory-based testing or verification to reach some clinical threshold you might try a company like NAMSA (no cronxeh, I didn't say NAMBLA). They offer testing kits and/or products for you to test the efficacy of your autoclave. You can either try some of their products or maybe call their tech support for some free advice.
  5. Oct 19, 2005 #4
    Fedegari has an excellent write up on F0 calculation. You can access the document at http://www.fedegari.com/techno.asp#fo

    I read somewhere that Stain121, which generally stays in the ocean depths, can resist the moist sterilization temperatures of 121 deg.C
  6. Oct 20, 2005 #5


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    Thanks for all of the help everyone. We had tried using spore strips for the validation, but the FDA wasn't satisfied. I found a few books that were helpful, especially Thermobacteriology in Food Processing by Stumbo. I think I've managed to find enough references to show that all of the microbes on my list are easier to kill than B. stearothermophilus, so I'm OK. Then again, I don't know jack squat about microbes and had never even heard of an autoclave a month ago. Thanks again.
  7. Oct 31, 2005 #6
    And tardigrades can survive +150 degrees without water,they are pretty much indestructible as bacterias.
  8. Oct 31, 2005 #7


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    Usually the testing kits for autoclaves are intended to detemine if your autoclave is actually working properly, not whether it is supposed to kill certain bacteria at a particular setting.

    If you're working with a specific bacteria that you're concerned about surviving extreme environments, I would think the safest approach would be to autoclave media known to contain the bacteria, and then culture it after autoclaving to see if they survived.
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