-difficult to test
~geochemically produced org. molecules
=> first rxns likely similar
-fermentation: a metabolic process whereby e-'s released 4rm nutrients are ultimately transferred to molecules obtained 4rm breakdown of those same nutrients. Typically organic acids and alcohols.
-Disproportional: 1 substrate is both the e- donor as well as the e- acceptor, producing 2 end products with distinct oxidation states, one higher, and one lower.
~ S° -> H3SO2 + H2S