Electrons are retained in:
- newly synthesized biomass
- reduced storage compounds
- methane
- acetate
- alcohols
- hydrogen
- other reduced secreted products
This is distinct from merely discarding electrons to a terminal acceptor.
Operational definition
Electron-fate category; revised title.
The routing of reducing equivalents into chemically reduced matter rather than immediately transferring them to a terminal oxidant.
It includes two distinguishable outcomes:
- reductive assimilation — electrons are retained in newly synthesized biomass;
- reduced-product formation — electrons are retained in products such as methane, alcohols, organic acids, hydrogen, or reduced storage compounds.
This is a higher-level electron-accounting category, not a single biochemical pathway. Respiration uses an environmentally supplied terminal electron acceptor, whereas fermentation ordinarily balances oxidation and reduction through substrate-derived intermediates; extracellular respiration places the acceptor beyond the cell boundary. (PubMed Central (PMC))