Can life exist in very salty water?

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand. Anyone know?

On Fri, 20 Feb 2004 11:06:02 +0100, "Dr. O" dr.o@xxxxx wrote, in
part:

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand. Anyone know?

Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example. I don't think
the salt concentration would materially affect the likelihood of
Martian life, which would have a biochemistry compatible with the
conditions it finds, since even a fairly high concentration wouldn't
prevent most chemical reactions from taking place.

John Savard
http://home.ecn.ab.ca/~jsavard/index.html

In article ,
lid (John Savard) wrote:

On Fri, 20 Feb 2004 11:06:02 +0100, "Dr. O" dr.o@xxxxx wrote, in
part:

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand. Anyone know?

Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example. I don't think
the salt concentration would materially affect the likelihood of
Martian life, which would have a biochemistry compatible with the
conditions it finds, since even a fairly high concentration wouldn't
prevent most chemical reactions from taking place.

But wouldn't the salt concentration affect the flow of water & ions
across cell walls?

--
Stephen Souter

http://www.edfac.usyd.edu.au/staff/souters/

In article ,
Stephen Souter wrote:
Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example...

But wouldn't the salt concentration affect the flow of water & ions
across cell walls?

Those are not *ordinary* microbes; they have special adaptations to living
in extremely salty water. There is a cost -- they have to spend energy
and materials on coping with that environment -- but it's not insuperable.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Stephen Souter wrote:
In article ,
lid (John Savard) wrote:

On Fri, 20 Feb 2004 11:06:02 +0100, "Dr. O" dr.o@xxxxx wrote, in
part:

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand. Anyone know?

Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example. I don't think
the salt concentration would materially affect the likelihood of
Martian life, which would have a biochemistry compatible with the
conditions it finds, since even a fairly high concentration wouldn't
prevent most chemical reactions from taking place.

But wouldn't the salt concentration affect the flow of water & ions
across cell walls?


Yes. But it depends a lot on the makeup of the cell walls aswell.

--
Sander

+++ Out of cheese error +++

Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand.

I don't know if the limit has been experimentally verified, but life on Earth
has adapted to brine pools on the ocean floor caused by brine seeps where the
water is six or seven times saltier than normal: so salty, indeed, that a
submersible is unable to dive into the stuff.
http://www.coast-nopp.org/resource_g...sical_param_ac
ts/saline.html

Given what extremophiles on Earth have adapted to, I suspect that single-celled
organisms, at least, could survive anywhere some form of liquid water exists.
Whether they would have evolved in such an environment is a much more complex
question.




Matt Bille
)
OPINIONS IN ALL POSTS ARE SOLELY THOSE OF THE AUTHOR

Dr. O wrote:
The MER's may have found evidence for salt water just below the
Martian surface. Salt water has a lower freezing temperature, but I'm
wondering how much salt concentration life can withstand. Anyone know?

Does 'salt' in this context refer to Sodium Chloride? If not, I imagine
that would make a difference.

Mike Maxwell

"Stephen Souter" wrote in message
...
In article ,
lid (John Savard) wrote:

On Fri, 20 Feb 2004 11:06:02 +0100, "Dr. O" dr.o@xxxxx wrote, in
part:

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering
how
much salt concentration life can withstand. Anyone know?

Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example. I don't think
the salt concentration would materially affect the likelihood of
Martian life, which would have a biochemistry compatible with the
conditions it finds, since even a fairly high concentration wouldn't
prevent most chemical reactions from taking place.

But wouldn't the salt concentration affect the flow of water & ions
across cell walls?

One would think. Nonetheless, life has been found in salt brines
with enormous concentrations of various salts. Far greater than
would be expected to be found on Mars.
Life has been found in almost unbelievable places.
In alkaline solutions that would dissolve bones if a very short time.
It has been found in extremely acidic conditions. It has been found
in the filters of the cooling water surrounding nuclear reactor cores.
It has been found fouling the filters in fuel tanks aboard jet aircraft.
It has been found spewing out of vents in the mid-ocean in water
that is over 600 degrees f.
Note, however, that no single species is capable of living in all
the above environments.

"Mike Maxwell" wrote in message
...
Dr. O wrote:
The MER's may have found evidence for salt water just below the
Martian surface. Salt water has a lower freezing temperature, but I'm
wondering how much salt concentration life can withstand. Anyone know?

Does 'salt' in this context refer to Sodium Chloride? If not, I imagine
that would make a difference.

It certainly would not be expected to be limited to Sodium Chloride.

Stephen Souter wrote in message ...
In article ,
lid (John Savard) wrote:

On Fri, 20 Feb 2004 11:06:02 +0100, "Dr. O" dr.o@xxxxx wrote, in
part:

The MER's may have found evidence for salt water just below the Martian
surface. Salt water has a lower freezing temperature, but I'm wondering how
much salt concentration life can withstand. Anyone know?

Earth life can do fairly well; although there are no fish in the Dead
Sea, there certainly are microbes there, for example. I don't think
the salt concentration would materially affect the likelihood of
Martian life, which would have a biochemistry compatible with the
conditions it finds, since even a fairly high concentration wouldn't
prevent most chemical reactions from taking place.

But wouldn't the salt concentration affect the flow of water & ions
across cell walls?

||Of particular note are the extreme halophiles or halobacteria,
||a group of archaea, which require at least 2 M of salt and are
||usually found in saturated solutions. These are the primary
||inhabitants of salt lakes and inland seas, such as the Dead Sea,
||where they tint the sediments bright colors.

||Among the adaptations that halophiles employ to survive in
||such environments are proteins designed to function in high
||ionic strength solution and maintaining high concentrations
||of inert solutes within their cytoplasm to reduce osmotic
||pressure. Most are unable to survive outside their high-salt
||native environment.
(http://en.wikipedia.org/wiki/Halophile)