So, I'm designing a race of sapient extraterrestrials for a series of short stories, and I've gotten to the point of designing their basic biochemistry, but I have a problem: Both their environment And (as I found out with How to replace glucose with ethanol?) their basic metabolic processes are highly acidic. Therefore, I must ask: How can I make Earthlike biochemistry more acid-tolerant?

Some requirements:

  • Amino acids (and proteins constructed from them) should be used, although if different amino acids must be used this is fine
  • The primary solvent must still be water, although it will have a lot of CO2 dissolved in it
  • Oxygen-based respiration should still be possible

The local atmosphere is as follows:

  • Pressure: 1.19atm
  • Composition: 78% N2, 17% O2, 2.2% CO2, 2.2% Ar, 0.5% H2O, 0.06% CH4, 0.03% NH3, 0.01% other

As mentioned in (what is a the time of writing this) the top answer to the question linked above, the local metabolic processes, in order to work the way I intend, must produce a lot of acidic compounds as intermediaries and byproducts, so take that into account when calculating acidity levels.

  • $\begingroup$ As written, this is too broad and fails the book test (seriously, all life on the planet?). We need to narrow the question. Knowing that you can't have "everything" without failing the book test, are you concerned with digestion? breathing? surface skin? plants? animals? hoof stock? primates? amoebas? bacteria? You need to focus on basically a single object (and that might fail the book test). $\endgroup$
    – JBH
    Jan 24, 2022 at 16:53

1 Answer 1



We actually have lots of life that lives in these extreme conditions already, just pick an example and read about it biochemistry.

Harder question will be how will you keep the environment acidic? Rocks will absorb strong acids and release CO2. Unless you change the whole star and planet evolution...


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