The Evolutionary Biology Lecture of the Week for July 24, 2006 is now available
at:

<a href="http://aics-research.com/lotw/>http://aics-research.com/lotw/

The talks center primarily around evolutionary biology, in all of its aspects:
cosmology, astronomy, planetology, geology, astrobiology, ecology, ethology,
biogeography, phylogenetics and evolutionary biology itself, and are presented
at a professional level, that of one scientist talking to another. All of the
talks were recorded live at conferences.

This is the tenth lecture in a summer-long series on the new science of
astrobiology.

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July 24, 2006

Part X: Astrobiology

Hyperthermophilic Microorganisms — A Possibility for Extraterrestrial Life?

Harald Huber, University of Regensburg

29 min.

"What is accomplished by fire is alchemy — whether in the furnace or in the
kitchen stove. And he who governs fire is Vulcan, even if he be a cook or a man
who tends the stove."

— Paracelsus, 1493-1541

Thirty years ago it was commonly stated in textbooks that no organic life could
survive at temperatures greater than 70°C, and that pasteurization would be
complete at 80°C.

In the intervening decades, we've since discovered life on this planet that
cannot survive at temperatures lower than 80°C, with many species of
hyperthermophilic archaea having their optimal growth temperatures greater than
that of boiling water. One recently discovered species, Pyrolobus fumerii,
reaches its upper temperature limit at an astounding 121°C, a temperature at
which protein denaturization would have previously been assumed to be complete.

Hyperthermophilic microorganisms are defined to be those organisms that their
exhibit optimal growth temperatures above 80°C and represent the upper
temperature border of life on our planet. They thrive in continental solfataric
(volcanic sulfurous steam) regimes and submarine hydrothermal systems, where
they form complex communities.

Hyperthermophiles are highly diverse in their morphologies and metabolic
properties. Most are anaerobes which use inorganic redox reactions as energy
sources, conditions reminiscent of the earliest Earth. These properties enable
them to grow in the absence of sunlight. They are also the most primitive
organisms known so far.