Redox potential
From Biocrawler, the free encyclopedia.
Many enzymatic reactions are oxidation-reduction reactions in which one compound is oxidized and another compound is reduced. The ability of an organism to carry out oxidation-reduction reactions depends on the oxidation-reduction state of the environment, or the Redox potential (Eh)
The redox potential is a relative value measured against the arbitrary 0 point of the normal hydrogen electrode. Any system or environment that accepts electrons from a normal hydrogen electrode is a half-cell that is defined as having a positive redox potentail; any system donates electrons to this hydrogen electrode is defined as having a negative redox potential. Eh is measured in mV. A high possitive Eh indicates an environment that favors oxidation reaction such as free oxygen. A low negative Eh indicates a strong reducing environment, such as free metals.
So strictly aerobic microorganisms can be active only at positive Eh values, whereas strict anaerobes can be active only at negative Eh values.
Redox affects the solubility of nutrients, especially metal ions.
Oxygen strongly affects redox potential.
