Fig. 5: Proposed mechanism of IHT-driven denitrification in CA.
From: Interspecies hydrogen transfer between cyanobacteria and symbiotic bacteria drives nitrogen loss
Cyanobacteria in CA generate H₂ under anoxic conditions through photosynthate fermentation catalyzed by [Nife] bidirectional hydrogenase (Hox). Hydrogenotrophic denitrifiers oxidize H2 coupled with the reduction of nitrate to gain energy. The dashed line represents the possible reaction when nitrogen is absent: Some cyanobacteria can generate H2 through nitrogen fixation, and the produced H2 may be used by hydrogenotrophic bacteria to support carbon fixation and growth.
