Investigation of the Ferredoxin’s Influence on the Anaerobic and Aerobic, Enzymatic H2 Production

Abstract

Ferredoxins are metalloproteins that deliver electrons to several redox partners, including [FeFe] hydrogenases that are potentially a component of biological H2 production technologies. Reduced ferredoxins can also lose electrons to molecular oxygen, which may lower the availability of electrons for cellular or synthetic reactions. Ferredoxins thus play a key role in diverse kinds of redox biochemistry, especially the enzymatic H2 production catalyzed by [FeFe] hydrogenases. We investigated how the yield of anaerobic and aerobic H2 production vary among the four different types of ferredoxins that are used to deliver electrons extracted from NADPH within the synthetic, fermentative pathway. We also assessed the electron loss due to O2 reduction by reduced ferredoxins within the pathway, for which the difference was as high as five-fold. Our findings provide valuable insights for further improving biological H2 production technologies and can also facilitate elucidation of mechanisms governing interactions between Fe–S cluster(s) and molecular oxygen.

High-rate Biohydrogen Production in Single-Chamber Microbial Electrolysis Cell Using Iron-Sulfide Modified Biocathode

“…With an in-depth understanding of microbial electrolysis cells technology (MEC), it can be a promising alternative approach for hydrogen production using the catalytic activity of microbes and reducing the energy demand (Catal et al 2015;Dizge et al 2019). At the anode of MEC, exoelectrogenic bacteria consume the organic substrate, generating electrons and protons, which are then transferred to the cathode, where microbes catalyze the hydrogen evolution reaction (HER) using ferredoxin complexes (Koo and Cha 2021). At neutral pH, an MEC typically requires a theoretical voltage of 0.118 V under standard conditionsusing acetate as substrate at anodewhich is significantly lower than abiotic water electrolysis (1.23 V) (Logan et al 2006).…”

“…The FeS material can be an even more intriguing catalyst for MECs as it can mimic ferredoxin complexes to expedite the biocatalytic HER (Mansy and Cowan 2004). Generally, the hydrogen-producing microbes utilize ferredoxin complexes, composed of FeS structures, to efficiently catalyze the HER within the cell membrane (Koo and Cha 2021). Therefore, it would be interesting to explore whether the FeS catalyst on the cathode in MEC promotes extracellular HER in microbes, allowing for the generation of high amounts of hydrogen.…”