# Why doesn't freezing kill bacteria? **URL:** \ **Category:** Factual Questions\ **Created:** [December 22, 2017, 3:36pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050 "2017-12-22T15:36:35Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 22, 2017, 3:36pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/1 "2017-12-22T15:36:35Z")
We know that you can heat bacteria to death but freezing them just preserves them. Why doesn’t freezing cause water to expand and rupture their cellular structure? Or at least cause their life-preserving processes to halt? Why don’t they need heat to live the same way as macro-animals? ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [December 22, 2017, 3:52pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/2 "2017-12-22T15:52:33Z")
This article may or may not have all the answers you’re looking for: > **[Colder Than Ice: Researchers Discover How Microbes Survive in Subfreezing...](https://blogs.scientificamerican.com/guest-blog/colder-than-ice-researchers-discover-how-microbes-survive-in-subfreezing-conditions/)** > > Most microbial researchers grow their microbes in petri-dishes to study how they grow and how they respond to damaging conditions. But researchers in Louisiana State University’s Department of Biological Sciences are doing something almost unheard... ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [December 22, 2017, 4:04pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/3 "2017-12-22T16:04:35Z")
Because bacteria evolve very rapidly and have been around for a very long time. There are few problems that they will encounter that they haven’t experienced a billion times before. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 6:25pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/4 "2017-12-22T18:25:50Z")
> [@Darren\_Garrison](#): > > Because bacteria evolve very rapidly and have been around for a very long time. There are few problems that they will encounter that they haven’t experienced a billion times before. An extension to this theme: Bacteria (over the millennia) have experienced many freeze-thaw cycles and have subsequently evolved survival techniques. Conversely, they probably have experienced few thaw-boiling cycles, hence their vulnerability to extreme heat? ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 6:33pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/5 "2017-12-22T18:33:22Z")
It also depends on the particular bacteria referred to… Normally found in foodstuffs?.. Normally found in volcanic hot water pools? ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [December 22, 2017, 6:57pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/6 "2017-12-22T18:57:39Z")
Right. There ARE bacteria that can survive boiling water. But those bacteria aren’t going to be found in your food, they’re going to be lurking in deep sea hydrothermal vents and hot springs. So freezing does kill some kinds of bacteria, but it isn’t going to be killing the stuff that makes your food go bad, because those strains of bacteria evolved mechanisms to survive freezing and thawing before multi-cellular life existed on this planet. And there are also plenty of species of multi-cellular organisms that can survive freezing. Yeah, humans and cats and dogs can’t. But other kinds can freeze solid and thaw out and get on with business. Or they at least have a stage in their life cycle that can survive freezing solid. If they couldn’t half of planet Earth would be a lifeless desert. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 7:02pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/7 "2017-12-22T19:02:52Z")
Well, maybe not quite half… But well put. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [December 22, 2017, 7:03pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/8 "2017-12-22T19:03:19Z")
> [@Lemur866](#): > > And there are also plenty of species of multi-cellular organisms that can survive freezing. Yeah, humans and cats and dogs can’t. Well, [full-sized ones, at least](http://www.sacbee.com/news/nation-world/national/article190636774.html). (Irrelevant aside–the baby and I share a birthday!) ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 7:07pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/9 "2017-12-22T19:07:53Z")
> [@Darren\_Garrison](#): > > (Irrelevant aside–the baby and I share a birthday!) Irrelevant aside- which baby?😃 BTW: Congratulations!🙂 ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [December 22, 2017, 7:13pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/10 "2017-12-22T19:13:49Z")
> [@ZurBob](#): > > Irrelevant aside- which baby? The baby from the 24-year frozen embryo in the linked article. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 7:23pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/11 "2017-12-22T19:23:25Z")
I didn’t bother with your link… My bad. I thought perhaps your child shared the same birthday as you… Sorry, I get it now. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [December 22, 2017, 8:31pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/12 "2017-12-22T20:31:58Z")
> [@Lemur866](#): > > And there are also plenty of species of multi-cellular organisms that can survive freezing. Yeah, humans and cats and dogs can’t. But other kinds can freeze solid and thaw out and get on with business. Or they at least have a stage in their life cycle that can survive freezing solid. If they couldn’t half of planet Earth would be a lifeless desert. Wood frogs can freeze during the winter and then thaw out in the spring, “coming back to life”. Now, it’s true that not 100% of their body freezes, but most of it does, including their blood. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [December 22, 2017, 10:43pm UTC](https://boards.straightdope.com/t/why-doesnt-freezing-kill-bacteria/805050/13 "2017-12-22T22:43:37Z")
> [@John\_Mace](#): > > Wood frogs can freeze during the winter and then thaw out in the spring, “coming back to life”. Now, it’s true that not 100% of their body freezes, but most of it does, including their blood. Just curious, what part doesn’t freeze?