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.
Subscribe to Journal
Get full journal access for 1 year
only $8.67 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
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.
Ringwood, A. E. Origin of the Earth and Moon (Springer, 1979).
Elkins‐Tanton, L. T. & Seager, S. Ranges of atmospheric mass and composition of super‐Earth exoplanets. Astrophys. J. 685, 1237–1246 (2008).
Rogers, L. A., Bodenheimer, P., Lissauer, J. J. & Seager, S. Formation and structure of low-density exo-Neptunes. Astrophys. J. 738, 59 (2011).
Walker, J. C. G. Evolution of the Atmosphere (Macmillan, 1977).
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).
Pierrehumbert, R. & Gaidos, E. Hydrogen greenhouse planets beyond the habitable zone. Astrophys. J. Lett. 734, L13 (2011).
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).
Stevenson, D. J. Life-sustaining planets in interstellar space? Nature 400, 32 (1999).
Kasting, J. F. in Treatise on Geochemistry 2nd edn, Vol. 6, 157–175 (Elsevier, 2013).
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).
De Wit, J. et al. Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1. Nat. Astron. 2, 214–219 (2018).
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).
Seager, S. & Sasselov, D. D. Theoretical transmission spectra during extrasolar giant planet transits. Astrophys. J. 537, 916–921 (2000).
Marois, C. et al. Direct imaging of multiple planets orbiting the star HR 8799. Science 322, 1348–1352 (2008).
Seager, S. & Deming, D. Exoplanet atmospheres. Annu. Rev. Astron. Astrophys. 48, 631–672 (2010).
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).
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).
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).
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).
Kaye, G. W. C. & Laby, T. H. Tables of Physical and Chemical Constants (Longman, 1986).
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).
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).
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).
Davies, B. S. J. & Rine, J. A role for sterol levels in oxygen sensing in Saccharomyces cerevisiae. Genetics 174, 191–201 (2006).
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).
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).
Schaefer, L. & Fegley, B.Jr Chemistry of atmospheres formed during accretion of the Earth and other terrestrial planets. Icarus 208, 438–448 (2010).
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).
Jo, J. Y. et al. Acute respiratory distress due to methane inhalation. Tuberc. Respir. Dis. 74, 120–123 (2013).
Shapiro, R. Origins: A Skeptic’s Guide to the Creation of Life on Earth (Bantam Dell Pub. Group, 1987).
Benner, S. A. et al. When did life likely emerge on Earth in an RNA‐first process? ChemSystemsChem 2, e1900035 (2020).
Seager, S., Bains, W. & Hu, R. Biosignature gases in H2-dominated atmospheres on rocky exoplanets. Astrophys. J. 777, 95 (2013).
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).
Cox, C. S. The survival of Escherichia coli in nitrogen atmospheres under changing conditions of relative humidity. Microbiology 45, 283–288 (1966).
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.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
E. coli culture OD measurement data.
Oxygen partial pressures in E. coli experiments
Composite photos of yeast cells in hemocytometer used for cell counting.
Yeast hemocytometer cell counting data.
Oxygen partial pressures in yeast experiments.
About this article
Cite this article
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