Hydrogenase and Nitrogenase: Key Catalysts in Biohydrogen Production

Abstract

Hydrogen with high energy content is considered to be a promising alternative clean energy source. Biohydrogen production through microbes provides a renewable and immense hydrogen supply by utilizing raw materials such as inexhaustible natural sunlight, water, and even organic waste, which is supposed to solve the two problems of “energy supply and environment protection” at the same time. Hydrogenases and nitrogenases are two classes of key enzymes involved in biohydrogen production and can be applied under different biological conditions. Both the research on enzymatic catalytic mechanisms and the innovations of enzymatic techniques are important and necessary for the application of biohydrogen production. In this review, we introduce the enzymatic structures related to biohydrogen production, summarize recent enzymatic and genetic engineering works to enhance hydrogen production, and describe the chemical efforts of novel synthetic artificial enzymes inspired by the two biocatalysts. Continual studies on the two types of enzymes in the future will further improve the efficiency of biohydrogen production and contribute to the economic feasibility of biohydrogen as an energy source.

Small-Molecule Fluorescent Probes for Binding- and Activity-Based Sensing of Redox-Active Biological Metals

“…Many of the unresolved questions about the redox-active metals are related to other biological systems. For example, the regulation of metalloproteins in bacteria is of interest for biohydrogen production, while copper proteins have been implicated in rust resistance in wheat . The application of fluorescent sensors to other organisms is less straightforward, as they generally possess a cell wall as well as a cell membrane, which is harder to traverse .…”

The Sea's best kept secret: the use of seaweed as a source of biohydrogen for clean and renewable energy

“…26 These biological catalysts are responsible for the metabolic mechanism associated with the formation and production of biohydrogen, with biological engineering required to further optimize the interaction of the enzymes with the substrate, in this case, organic materials. 27,28 However, studies suggest that the hydrogenase enzyme is sensitive to high concentrations of oxygen (5.0 vol%), which in turn, directly inhibits biohydrogen production, 29 and so it is important to keep conditions anaerobic and monitor oxygen levels carefully. It is worth noting that bio-engineered enzymatic treatments, especially when applied on an industrial scale, might become expensive due to their sensitivity and specificity.…”

H₂ Production from Methyl Viologen–Dependent Hydrogenase Activity Monitored by Gas Chromatography

“…With efficient biochemical mechanisms, it is possible to develop an environmentally friendly process for H 2 production at ambient conditions by taking advantage of hydrogenase-expressing microorganisms. Among the enzymes with different catalytic sites, [FeFe]-hydrogenase is more efficient than [NiFe]- and [Fe]-types in H 2 production with NADH as a reductant in a natural mechanism, as shown in Figure S1 in the Supporting materials ( Ogo et al, 2020 ; Xuan et al, 2023 ). To screen microorganisms carrying active hydrogenase in a laboratory scale, methyl viologen (MV 2+ ), which is compatible with many enzymes ( Orgill et al, 2015 ), can also be used as an artificial reductant in this reaction.…”