Fig. 7: A model illustrating the molecular mechanisms underlying the humic substances-dediated coupled processes of extracellular electron transfer (EET) and uptake by denitrifiers.
From: Electron shuttling promotes denitrification and mitigates nitrous oxide emissions in lakes
Electrons generated by EET microbes through glycolysis or dissimilatory sulfur reduction are transferred stepwise to extracellular electron shuttles (i.e., humic substances). These electrons are then further transferred via a series of cytochromes to denitrification enzymes. DHNA, 1,4-dihydroxy-2-naphthoyl-CoA; DMK demethylmenaquinone; IPP isopentenyl pyrophosphate; OMC outer membrane cytochrome; HPMC heme-containing periplasmic membrane-bound cytochrome; PSC periplasmic soluble cytochrome; CSC complex stabilizing cytochrome; Nap periplasmic nitrate reductase; Nar membrane-bound nitrate reductase; Nir nitrite reductase; Nor nitric oxide reductase; Nos nitrous oxide reductase.
