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Appl Environ Microbiol. 2000 Aug;66(8):3230-3.

Metabolic activity of permafrost bacteria below the freezing point.

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  • 1Department of Biological Science, Florida State University, Tallahassee 32306-1100, USA.
  • 2FL St U, Tallahassee
  • 3NASA ARC

Abstract

Metabolic activity was measured in the laboratory at temperatures between 5 and -20 degrees C on the basis of incorporation of (14)C-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5 degrees C) to 20 days (-10 degrees C) to ca. 160 days (-20 degrees C). The curves reached the stationary phase at different levels, depending on the incubation temperature. We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature.

PMID:
10919774
PMCID:
PMC92138
[PubMed - indexed for MEDLINE]
Free PMC Article
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