Laboratory Studies On The Viability Of Life In H2-dominated Exoplanet Atmospheres


The simplified schematic of the cell culture growth experiment for E. coli or yeast S. cerevisiae. A) Preparation of the starter culture from which the experiment cultures of yeast and E. coli are derived. B) Preparation of the experiment bottles before inoculation of the anoxic media with target organism. C) Growth of the experimental cultures in a shaking incubator. The growth of the culture was monitored spectroscopically by OD600 measurements (E. coli) or by direct cell counting with a hemocytometer (yeast) (not shown). See the main text and the supplementary information for a detailed description of the procedure.

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 (E. 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 (e.g., nitrous oxide, ammonia, methanethiol, dimethylsulfide, carbonyl sulfide, and isoprene). This work demonstrates the utility of lab experiments to better identify which kinds of alien environments can host some form of possibly detectable life.

S. Seager, J. Huang, J.J. Petkowski, M. Pajusalu

Comments: Nature Astronomy this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Quantitative Methods (q-bio.QM)
Cite as: arXiv:2005.01668 [astro-ph.EP] (or arXiv:2005.01668v1 [astro-ph.EP] for this version)
Submission history
From: Sara Seager
[v1] Mon, 4 May 2020 17:22:04 UTC (1,649 KB)
https://arxiv.org/abs/2005.01668
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