Reduced Phosphorus in Bacteria

Several anaerobic bacteria are now known to contain ferredoxins with potentials that are low enough (e.g. - 0.4 V) to make them candidates for phosphate reduction. Therefore it seems thermodynamically possible that anaerobic microorganisms could synthesise reduced P compounds, for example, PH3. The literature on this appears to be sparse, however there are hints and debates that this may be the case. 

Consideration of the oxidation state diagram (Fig. 1) shows that PH3 is a very strong reducing agent. Oxidation to phosphate is an 8-electron process. It may be predicted on thermodynamic grounds that, in mammalian systems, reduced forms of phosphorus will be very reactive, and that oxidation pathways are likely to dominate their biological chemistry. 

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