Bacteria Physiology in Low Temperatures
Country: United States
Date: August 2006
What happens to bacteria functioning in low temperature?
Like all chemical reactios, biochemical reactions (even those
catalyzed by enzymes) slow down by a factor of 2-3 for every 10
degrees C lowering of the temperature. At a certain temperature, some
enzymes in a bacterium may fold incorrectly and as a result stop
catalyzing all together thus causing death of the cell.
Ron Baker, Ph.D.
Your question is very timely. In the 12-18 August issue of the journal "NEW
SCIENTIST" is an article on exactly this topic, entitled "Sub-Zero
Survivors". It is mind boggling. Historically, microbiologists have
estimated that the "absolute zero" of metabolism of microbes was about -20C.
This put a damper on the prospects of finding "life" on Mars, the moons of
Jupiter etc. which never rise above about -40C. However, research has shown
that a species of bacteria "Colwellia 34H" thrive at temperatures of
about -50C. because the freezing of salt water excludes salt from the liquid
phase, leaving liquid water for this bacterium to exist.
Another environment is the nanofilms of glassy water that exists at even
lower temperatures. In this environment, the viscosity of glassy water is so
high that it cannot crystallize and is available to sustain microbial life
(PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, vol.102, pg 10913). There
is even evidence, although not universally accepted, that cells can survive
at the boiling point of liquid nitrogen (-196 C.)!!
There are other examples of cellular life at intermediate temperatures.
Of course, metabolism slows, but the fact that there is even a hint of life
at these low temperatures is fascinating.
Check the website: www.newscientist.com
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Update: June 2012