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Name: Manjiri
Status: Student
Grade:  9-12
Location: N/A
Country: United States
Date: August 2006


Question:
What happens to bacteria functioning in low temperature?



Replies:
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

Vince Calder



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