# Why autoclave? **URL:** \ **Category:** Factual Questions\ **Created:** [May 13, 2009, 8:42pm UTC](https://boards.straightdope.com/t/why-autoclave/496340 "2009-05-13T20:42:33Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [May 13, 2009, 8:42pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/1 "2009-05-13T20:42:33Z")
In science and medicine, the autoclave is the standard method of sterilization. It uses high pressure so that liquids can be brought above 100° C (usually 121° or 135°). It’ll kill everything\*. Or at least it kills most pathogens\*\*. Well, it still seems to kill enough for everyday purposes in the lab or hospital. But what makes autoclaving necessary in the first place? I take it someone, many decades ago, decided that ordinary boiling wasn’t enough, since some pathogen was surviving. What is it that survives 100° at standard pressures? \*Well, mostly everything. [This bacteria](http://en.wikipedia.org/wiki/Strain_121) laughs at the autoclave, kicks back, and enjoys a nice relaxing dip in the hot tub. Though it has no interest in us, thankfully. \*\*Except prions, which cause Mad Cow disease. ---
**Author:** ![Nunavut\_Boy](https://avatars.discourse-cdn.com/v4/letter/n/e95f7d/32.png) [@Nunavut\_Boy](https://boards.straightdope.com/u/Nunavut_Boy)\ **Post date:** [May 13, 2009, 9:17pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/2 "2009-05-13T21:17:44Z")
I believe spores are the answer. Some spores (among other things I’m not remembering, I’m sure) can survive boiling and bleaching. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 13, 2009, 10:02pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/3 "2009-05-13T22:02:48Z")
Botulism spores are the standard “really resistant bacterial form”. I don’t know if your lab’s autoclave people use them, but you can buy vials of botulism spores for testing if your autoclave is working properly. The idea is that you put a vial in with your run, and when it comes out, you incubate it like a regular bacterial culture. There’s a pH indicator in there that tells you if anything grows. If it does, then you know your autoclave treatment wasn’t sufficient to kill all spores. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [May 13, 2009, 11:09pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/4 "2009-05-13T23:09:49Z")
> [@Smeghead](#): > > Botulism spores are the standard “really resistant bacterial form”. I don’t know if your lab’s autoclave people use them, but you can buy vials of botulism spores for testing if your autoclave is working properly. The idea is that you put a vial in with your run, and when it comes out, you incubate it like a regular bacterial culture. There’s a pH indicator in there that tells you if anything grows. If it does, then you know your autoclave treatment wasn’t sufficient to kill all spores. Ah. For some reason I thought that botulism spores could be killed eventually at 100°. For home canning… how do you sterilize then? My understanding was that thorough boiling was enough, but problems arose when the whole jar didn’t reach 100°. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [May 13, 2009, 11:51pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/5 "2009-05-13T23:51:36Z")
> [@lazybratsche](#): > > For home canning… how do you sterilize then? My understanding was that thorough boiling was enough, but problems arose when the whole jar didn’t reach 100°. The USDA and other resources recommend pressure canning, rather than hot water bath canning, for not-very-acidic foods, to avoid botulism. [Linkie](http://www.uga.edu/nchfp/how/can_home.html) from the National Center for Home Food Preservation at the University of Georgia. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [May 13, 2009, 11:54pm UTC](https://boards.straightdope.com/t/why-autoclave/496340/6 "2009-05-13T23:54:08Z")
> [@lazybratsche](#): > > For home canning… how do you sterilize then? My understanding was that thorough boiling was enough, but problems arose when the whole jar didn’t reach 100°. Pressure canning, when indicated. ---
**Author:** ![lazybratsche](https://avatars.discourse-cdn.com/v4/letter/l/ba8739/32.png) [@lazybratsche](https://boards.straightdope.com/u/lazybratsche)\ **Post date:** [May 14, 2009, 12:34am UTC](https://boards.straightdope.com/t/why-autoclave/496340/7 "2009-05-14T00:34:59Z")
Got it. Ignorance fought. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [May 14, 2009, 12:41am UTC](https://boards.straightdope.com/t/why-autoclave/496340/8 "2009-05-14T00:41:04Z")
If you kept it at 100 degrees, it would kill botulism…eventually. There’s an equation out there that lets you swap temperature, pressure, and time back and forth. I learned it in my food micro class, but that was close to a decade ago.