Iron deficiency suppresses the Fenton reaction and boosts photosynthetic H2 production in bisulfite-treated Chlamydomonas cells

Abstract

Adding bisulfite is a significant strategy to enhance H2 photoproduction, but it adversely affects photosystem II (PSII) activity in microalgae, consequently limiting H2 production. Nevertheless, the exact mechanism through which bisulfite disrupts PSII remains unclear. Here, the addition of NaHSO3 to Chlamydomonas reinhardtii cultures suppresses growth by inducing iron poisoning through the Fenton reaction, driven by reduced iron demand and the resultant accumulation of iron. Consequently, the removal of iron from C. reinhardtii cultures eliminates the iron poisoning triggered by the Fenton reaction. This, in turn, mitigates PSII impairment and leads to a significant increase in photosynthetic H2 production in C. reinhardtii cells. Collectively, these discoveries unveil the precise mechanism by which bisulfite disrupts PSII, opening up a new avenue for substantially enhancing green hydrogen production from microalgae through the bisulfite addition strategy.