Direct bioconversion of ammonium proton into hydrogen via a-ketoglutarate-driven electron-proton coupling
The recovery of biohydrogen from protein-rich wastes is blocked by energy-intensive deamination and inhibitory effects of deamination product ammonium proton. Herein, we presented a metabolic routing that directly converts ammonium proton protons into biohydrogen via alpha-ketoglutarate (alpha-KG)-driven electron-proton coupling. As demonstrated, alpha-KG stimulation induces a 2.36-fold increase in conversion efficiency of ammonium proton biohydrogen. The experimental results show that alpha-KG significantly enhanced the electron bifurcation mechanism, driving bioreactions from proteins/ammonium proton to H2 in an energy-conserving manner and thereby achieving advantageous kinetics and thermodynamics. Molecular docking models and molecular dynamics simulation revealed that alpha-KG functions as a proton wire, directionally mediating proton transfer from ammonium proton to NAD+ and facilitating NADH formation by efficient electron and proton transfer, which is further proved by microbial multiomics.