Laboratory studies on the viability of life in H2-dominated exoplanet atmospheres

Abstract

Theory and observation for the search for life on exoplanets via atmospheric ‘biosignature gases’ is accelerating, motivated by the capabilities of the next generation of space- and ground-based telescopes. The most observationally accessible rocky planet atmospheres are those dominated by molecular hydrogen gas, because the low density of H2 gas leads to an expansive atmosphere. The capability of life to withstand such exotic environments, however, has not been tested in this context. We demonstrate that single-celled microorganisms (Escherichia coli and yeast) that normally do not inhabit H2-dominated environments can survive and grow in a 100% H2 atmosphere. We also describe the astonishing diversity of dozens of different gases produced by E. coli, including many already proposed as potential biosignature gases (for example, nitrous oxide, ammonia, methanethiol, dimethylsulfide, carbonyl sulfide and isoprene). This work demonstrates the utility of laboratory experiments to better identify which kinds of alien environments can host some form of possibly detectable life.

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Fig. 1: The simplified schematic of the cell culture growth experiment for E. coli or yeast S. cerevisiae.
Fig. 2: Growth curves of E. coli.
Fig. 3: Growth curves of yeast.
Fig. 4: Spectral features of gases produced by E. coli with existing data.

Data availability

We supplied the source data for Figs. 2 and 3, which you can find as supplementary files as well as at https://dspace.mit.edu/handle/1721.1/123824. The other data that support the plots within this paper and other findings of this study are available from the authors on request.

Change history

  • 14 May 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.

References

  1. 1.

    Ringwood, A. E. Origin of the Earth and Moon (Springer, 1979).

  2. 2.

    Elkins‐Tanton, L. T. & Seager, S. Ranges of atmospheric mass and composition of super‐Earth exoplanets. Astrophys. J. 685, 1237–1246 (2008).

    ADS  Article  Google Scholar 

  3. 3.

    Rogers, L. A., Bodenheimer, P., Lissauer, J. J. & Seager, S. Formation and structure of low-density exo-Neptunes. Astrophys. J. 738, 59 (2011).

    ADS  Article  Google Scholar 

  4. 4.

    Walker, J. C. G. Evolution of the Atmosphere (Macmillan, 1977).

  5. 5.

    Levi, A., Kenyon, S. J., Podolak, M. & Prialnik, D. H-Atmospheres of icy super-Earths formed in situ in the outer solar system: an application to a possible planet nine. Astrophys. J. 839, 111 (2017).

    ADS  Article  Google Scholar 

  6. 6.

    Pierrehumbert, R. & Gaidos, E. Hydrogen greenhouse planets beyond the habitable zone. Astrophys. J. Lett. 734, L13 (2011).

    ADS  Article  Google Scholar 

  7. 7.

    Hu, R., Seager, S. & Yung, Y. L. Helium atmospheres on warm Neptune- and sub-Neptune-sized exoplanets and applications to GJ 436b. Astrophys. J. 807, 8 (2015).

    ADS  Article  Google Scholar 

  8. 8.

    Stevenson, D. J. Life-sustaining planets in interstellar space? Nature 400, 32 (1999).

    ADS  Article  Google Scholar 

  9. 9.

    Kasting, J. F. in Treatise on Geochemistry 2nd edn, Vol. 6, 157–175 (Elsevier, 2013).

  10. 10.

    Zahnle, K. J., Gacesa, M. & Catling, D. C. Strange messenger: a new history of hydrogen on Earth, as told by xenon. Geochim. Cosmochim. Acta 244, 56–85 (2019).

    ADS  Article  Google Scholar 

  11. 11.

    De Wit, J. et al. Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1. Nat. Astron. 2, 214–219 (2018).

    ADS  Article  Google Scholar 

  12. 12.

    Diamond-Lowe, H., Berta-Thompson, Z., Charbonneau, D. & Kempton, E. M.-R. Ground-based optical transmission spectroscopy of the small, rocky exoplanet GJ 1132b. Astron. J. 156, 42 (2018).

    ADS  Article  Google Scholar 

  13. 13.

    Seager, S. & Sasselov, D. D. Theoretical transmission spectra during extrasolar giant planet transits. Astrophys. J. 537, 916–921 (2000).

    ADS  Article  Google Scholar 

  14. 14.

    Marois, C. et al. Direct imaging of multiple planets orbiting the star HR 8799. Science 322, 1348–1352 (2008).

    ADS  Article  Google Scholar 

  15. 15.

    Seager, S. & Deming, D. Exoplanet atmospheres. Annu. Rev. Astron. Astrophys. 48, 631–672 (2010).

    ADS  Article  Google Scholar 

  16. 16.

    Madhusudhan, N., Knutson, H., Fortney, J. J. & Barman, T. in Protostars and Planets VI (eds Beuther, H. et al.) 739–762 (University of Arizona Press, 2014).

  17. 17.

    Balch, W. E., Fox, G. E., Magrum, L. J., Woese, C. R. & Wolfe, R. S. Methanogens: reevaluation of a unique biological group. Microbiol. Rev. 43, 260–296 (1979).

    Article  Google Scholar 

  18. 18.

    Peters, V., Janssen, P. H. & Conrad, R. Efficiency of hydrogen utilization during unitrophic and mixotrophic growth of Acetobacterium woodii on hydrogen and lactate in the chemostat. FEMS Microbiol. Ecol. 26, 317–324 (1998).

    Article  Google Scholar 

  19. 19.

    Pajusalu, M., Borlina, C. S., Seager, S., Ono, S. & Boask, T. Open-source sensor for measuring oxygen partial pressures below 100 microbars. PLoS ONE 13, e020667 (2018).

    Article  Google Scholar 

  20. 20.

    Kaye, G. W. C. & Laby, T. H. Tables of Physical and Chemical Constants (Longman, 1986).

  21. 21.

    Pavlov, A. A. & Kasting, J. F. Mass-independent fractionation of sulfur isotopes in Archean sediments: strong evidence for an anoxic Archean atmosphere. Astrobiology 2, 27–41 (2002).

    ADS  Article  Google Scholar 

  22. 22.

    Buzas, Z. S., Dallmann, K. & Szajani, B. Influence of pH on the growth and ethanol production of free and immobilized Saccaromyces cerevisiae cells. Biotechnol. Bioeng. 34, 882–884 (1989).

    Article  Google Scholar 

  23. 23.

    Waldbauer, J. R., Newman, D. K. & Summons, R. E. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life. Proc. Natl Acad. Sci. USA 108, 13409–13414 (2011).

    ADS  Article  Google Scholar 

  24. 24.

    Davies, B. S. J. & Rine, J. A role for sterol levels in oxygen sensing in Saccharomyces cerevisiae. Genetics 174, 191–201 (2006).

    Article  Google Scholar 

  25. 25.

    Takishita, K. et al. Lateral transfer of tetrahymanol-synthesizing genes has allowed multiple diverse eukaryote lineages to independently adapt to environments without oxygen. Biol. Direct 7, 5 (2012).

    Article  Google Scholar 

  26. 26.

    Gregory, S. P., Barnett, M. J., Field, L. P. & Milodowski, A. E. Subsurface microbial hydrogen cycling: natural occurrence and implications for industry. Microorganisms 7, 53 (2019).

    Article  Google Scholar 

  27. 27.

    Schaefer, L. & Fegley, B.Jr Chemistry of atmospheres formed during accretion of the Earth and other terrestrial planets. Icarus 208, 438–448 (2010).

    ADS  Article  Google Scholar 

  28. 28.

    Levi, A., Sasselov, D. & Podolak, M. Structure and dynamics of cold water super-Earths: the case of occluded CH4 and its outgassing. Astrophys. J. 792, 125 (2014).

    ADS  Article  Google Scholar 

  29. 29.

    Jo, J. Y. et al. Acute respiratory distress due to methane inhalation. Tuberc. Respir. Dis. 74, 120–123 (2013).

    Article  Google Scholar 

  30. 30.

    Shapiro, R. Origins: A Skeptic’s Guide to the Creation of Life on Earth (Bantam Dell Pub. Group, 1987).

  31. 31.

    Benner, S. A. et al. When did life likely emerge on Earth in an RNA‐first process? ChemSystemsChem 2, e1900035 (2020).

    Article  Google Scholar 

  32. 32.

    Seager, S., Bains, W. & Hu, R. Biosignature gases in H2-dominated atmospheres on rocky exoplanets. Astrophys. J. 777, 95 (2013).

    ADS  Article  Google Scholar 

  33. 33.

    Linstrom, P. J. & Mallard, W. G. The NIST Chemistry Webbook: a chemical data resource on the Internet. J. Chem. Eng. Data 46, 1059–1063 (2001).

    Article  Google Scholar 

  34. 34.

    Cox, C. S. The survival of Escherichia coli in nitrogen atmospheres under changing conditions of relative humidity. Microbiology 45, 283–288 (1966).

    Google Scholar 

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Acknowledgements

We thank A. Babbin for use of his laboratory and S. Smirga for assistance. We thank M. Slabicki and C. de Boer for providing us with a sample of yeast Saccharomyces cerevisiae S288C. We also thank J. Petkowska-Hankel for help with Fig. 1 and Z. Zhan for Fig. 4. Seed funding for this work came from the Templeton Foundation Grant ‘The Alien Earths Initiative’, ID 43769. Funding for this work came from the MIT Professor Amar G. Bose Research Grant Program.

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Authors

Contributions

S.S. conceived the original idea and wrote the paper with the help of J.J.P. and M.P. M.P. designed and implemented the experimental set-up. S.S. and M.P. planned the experiments with the help of J.J.P. J.H. and M.P. performed the experiments with the help of J.J.P. All authors analysed the data.

Corresponding author

Correspondence to S. Seager.

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Supplementary information

Supplementary Information

Supplementary Materials and Methods, Figs. 1–3 and Tables 1–3.

Source data

Source Data Fig. 2

E. coli culture OD measurement data.

Source Data Supplementary Fig. 2

Oxygen partial pressures in E. coli experiments

Source Data Fig. 3

Composite photos of yeast cells in hemocytometer used for cell counting.

Source Data Fig. 3

Yeast hemocytometer cell counting data.

Source Data Supplementary Fig. 3

Oxygen partial pressures in yeast experiments.

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Seager, S., Huang, J., Petkowski, J.J. et al. Laboratory studies on the viability of life in H2-dominated exoplanet atmospheres. Nat Astron (2020). https://doi.org/10.1038/s41550-020-1069-4

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