Paper: Hyperthermophiles in the history of life

Philosophical Transactions of the Royal Society B: Biological Sciences
ISSN: 0962-8436 (Paper) 1471-2970 (Online)
Issue: Volume 361, Number 1474 / October 29, 2006

Pages: 1837 - 1843
DOI: 10.1098/rstb.2006.1907
Special Issue: Discussion Meeting Issue 'Conditions for the emergence of
life on the early Earth' organized by S. Leach, I. Smith and C. Cockell

Hyperthermophiles in the history of life

Karl O. Stetter

Abstract:
Today, hyperthermophilic ('superheat-loving') bacteria and archaea are found
within high-temperature environments, representing the upper temperature
border of life. They grow optimally above 80°C and exhibit an upper
temperature border of growth up to 113°C. Members of the genera, Pyrodictium
and Pyrolobus, survive at least 1h of autoclaving. In their basically
anaerobic environments, hyperthermophiles (HT) gain energy by inorganic
redox reactions employing compounds like molecular hydrogen, carbon dioxide,
sulphur and ferric and ferrous iron. Based on their growth requirements, HT
could have existed already on the early Earth about 3.9Gyr ago. In
agreement, within the phylogenetic tree of life, they occupy all the short
deep branches closest to the root. The earliest archaeal phylogenetic
lineage is represented by the extremely tiny members of the novel kingdom of
Nanoarchaeota, which thrive in submarine hot vents. HT are very tough
survivors, even in deep-freezing at ?140°C. Therefore, during impact ejecta,
they could have been successfully transferred to other planets and moons
through the coldness of space.

Source: The Royal Society
http://www.journals.royalsoc.ac.uk/link.asp?id=20410744H1L331W0

Posted by
Robert Karl Stonjek


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