[Jimbee (OP)]

What does freezing do to germs? (By freezing of course I mean the temperature when water turns to a solid, 32 degrees F or 0 degrees C.) It seems to put some of them into suspended animation. And now that the arctic ice caps are melting, some bacteria that haven't been around for thousands of years are coming back.

I know the freezing point of water is not the same as absolute zero. Absolute zero is the temperature where all atomic motion stops, 459.67 degrees F, -273.15 degrees C (or just 0 Kelvin, 0 K). Like I said, 32 degrees is just when water turns to solid. So the germs are alive, they just can't move. So why does that make them live for thousands of years that way?

[evan_au]

Re: "why does [freezing] make them live for thousands of years that way?"
I think it is the opposite - freezing will kill most organisms. There are a few that can survive freezing and thawing - and it takes careful scientific work to demonstrate this,

Rationale
When pure water drops to 0C, it tends to form ice crystals.
- Large ice crystals forming within cells will break the cells open and kill them. This is what happens to most organisms.
- Some organisms can remain active slightly below 0C because their environment is not pure water
- Some types of organisms survive freezing by expelling water (and absorbing it again when temperatures rise)
- Other types of organisms survive freezing by producing anti-freeze chemicals which prevent growth of ice crystals, allowing the cells to survive freezing and thawing intact.
- Organisms held in suspended animation will suffer radiation damage, so they need robust DNA repair mechanisms.
- And other organisms survive freezing weather by traveling to Spain for the winter!

[paul cotter]

What about bacterial spores? It is so long since I did micro, I can't remember anything about their low temperature susceptibilities though they are very resilient to other stressors.

[Bored chemist]

What does freezing do to germs? (By freezing of course I mean the temperature when water turns to a solid, 32 degrees F or 0 degrees C.) It seems to put some of them into suspended animation. And now that the arctic ice caps are melting, some bacteria that haven't been around for thousands of years are coming back.

I know the freezing point of water is not the same as absolute zero. Absolute zero is the temperature where all atomic motion stops, 459.67 degrees F, -273.15 degrees C (or just 0 Kelvin, 0 K). Like I said, 32 degrees is just when water turns to solid. So the germs are alive, they just can't move. So why does that make them live for thousands of years that way?

Re. "Absolute zero is the temperature where all atomic motion stops", actually, no, it doesn't.

" So the germs are alive, they just can't move. So why does that make them live for thousands of years that way?"
If they can't do anything, they can't die.
They live by default.