X-Message-Number: 29802
Date: Thu, 30 Aug 2007 09:46:57 -0700 (PDT)
From: 
Subject: microbe longevity in permafrost

Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13455-60. Epub 2007 Aug 8.
From the Cover: Fossil genes and microbes in the oldest ice on Earth.
     Bidle KD, Lee S, Marchant DR, Falkowski PG. *Environmental Biophysics
and Molecular Ecology Program, Institute of Marine and Coastal Sciences,
and Department of Geological Sciences, Rutgers, The State University of
New Jersey, New Brunswick, NJ 08901.
    Although the vast majority of ice that formed on the Antarctic
continent over the past 34 million years has been lost to the oceans,
pockets of ancient ice persist in the Dry Valleys of the Transantarctic
Mountains. Here we report on the potential metabolic activity of microbes
and the state of community DNA in ice derived from Mullins and upper
Beacon Valleys. The minimum age of the former is 100 ka, whereas that of
the latter is approximately 8 Ma, making it the oldest known ice on
Earth. In both samples, radiolabeled substrates were incorporated into
macromolecules, and microbes grew in nutrient-enriched meltwaters, but
metabolic activity and cell viability were critically compromised with
age. Although a 16S rDNA-based community reconstruction suggested
relatively low bacterial sequence diversity in both ice samples,
metagenomic analyses of community DNA revealed many diverse
orthologs to extant metabolic genes. Analyses of five ice samples,
spanning the last 8 million years in this region, demonstrated an
exponential decline in the average community DNA size with a half-life of
approximately 1.1 million years, thereby constraining the geological
preservation of microbes in icy environments and the possible exchange of
genetic material to the oceans.
PMID: 17686983

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=29802