Movatterモバイル変換

[0]ホーム
URL:

Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
Thehttps:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

NIH NLM Logo
Log inShow account info
Access keysNCBI HomepageMyNCBI HomepageMain ContentMain Navigation
pubmed logo
Advanced Clipboard
User Guide

Full text links

Atypon full text link Atypon Free PMC article
Full text links

Actions

Share

.2005 Dec 20;102(51):18292-6.
doi: 10.1073/pnas.0507601102. Epub 2005 Dec 7.

Microbial origin of excess methane in glacial ice and implications for life on Mars

Affiliations

Microbial origin of excess methane in glacial ice and implications for life on Mars

H C Tung et al. Proc Natl Acad Sci U S A..

Abstract

Methane trapped in the 3,053-m-deep Greenland Ice Sheet Project 2 ice core provides an important record of millennial-scale climate change over the last 110,000 yr. However, at several depths in the lowest 90 m of the ice core, the methane concentration is up to an order of magnitude higher than at other depths. At those depths we have discovered methanogenic archaea, the in situ metabolism of which accounts for the excess methane. The total concentration of all types of microbes we measured with direct counts of Syto-23-stained cells tracks the excess of methanogens that we identified by their F420 autofluorescence and provides independent evidence for anomalous layers. The metabolic rate we estimated for microbes at those depths is consistent with the Arrhenius relation for rates found earlier for microbes imprisoned in rock, sediment, and ice. It is roughly the same as the rate of spontaneous macromolecular damage inferred from laboratory data, suggesting that microbes imprisoned in ice expend metabolic energy mainly to repair damage to DNA and amino acids rather than to grow. Equating the loss rate of methane recently discovered in the Martian atmosphere to the production rate by possible methanogens, we estimate that a possible Martian habitat would be at a temperature of approximately 0 degrees C and that the concentration, if uniformly distributed in a 10-m-thick layer, would be approximately 1 cell per ml.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.
Methane concentration as a function of depth in the GISP2 ice core (ref. ; E. Brook, personal communication). Below 2,950 m, the scale is expanded to show the anomalously high methane values at 2,954, 3018, and 3,036 m.
Fig. 2.
Fig. 2.
Microbial concentration as a function of radial distance from the surface to the center of the GISP2 ice core at a depth of 500 m. Some of the outermost 3.8 cm of ice had clearly been contaminated by either the drilling fluid used to cut the core or subsequent handling.
Fig. 3.
Fig. 3.
Concentrations of all cells (Upper) and of methanogens (Lower). Syto-23 stain was used to visualize fluorescence of all cells, and F420 autofluorescence was used to image methanogenic cells. Measurements were made with both Syto-23 and F420 on the same samples at all depths except at 1,887 m. Error bars indicate counting statistics. Upper limits at 90 cells per ml correspond to a null count at an 84% confidence level. At depths ≈1 m above and below the values at 2,954, 3,018, and 3,036 m, the concentrations drop to background values, just as was the case for methane in Fig. 1.
Fig. 4.
Fig. 4.
Temperature dependence of metabolic rate of microbial communities imprisoned in ice, rock, and sea sediment. Metabolic products are shown in parentheses. Solid-red squares show the rates at temperatures from 24 to –40°C; the rate for cells in GISP2 silty ice is shown at –9.5°C (13). Solid-blue diamonds denote the present results for methanogens in GISP2 ice at 2,954 and 3,018 m, and solid-green triangles denote the present results for CO2 producers at the same depths.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Blunier, T. & Brook, E. (2001) Science 291, 109–112. - PubMed
    1. Priscu, J. C. & Christner, B. (2004) in Microbial Diversity and Bioprospecting, ed. Bull, A. T. (Am. Soc. Microbiol., Washington, DC), pp. 130–145.
    1. Gaidos, E., Lanoil, B., Thorsteinsson, T., Graham, A., Skidmore, M., Han, S.-K., Rust, T. & Popp, B. (2004) Astrobiology 4, 327–344. - PubMed
    1. Bulat, S. A., Alekhina, I. A., Blot, M., Petit, J.-R., de Angelis, M., Wagenbach, D., Lipenkov, V. Y., Vasilyeva, L. P., Wloch, D. M., Raynaud, D., et al. (2004) Int. J. Astrobiology 3, 1–12.
    1. Sheridan, P. P., Miteva, V. I. & Brenchley, J. E. (2003) Appl. Environ. Microbiol. 69, 2153–2160. - PMC - PubMed

Publication types

MeSH terms

Substances

Related information

LinkOut - more resources

Full text links
Atypon full text link Atypon Free PMC article
Cite
Send To

NCBI Literature Resources

MeSHPMCBookshelfDisclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

[8]ページ先頭
©2009-2025 Movatter.jp