Microalgal Hydrogen Production: Achievements and Perspectives
CHAPTER 4: The Physiology of the Bidirectional NiFe-hydrogenase in Cyanobacteria and the Role of Hydrogen Throughout the Evolution of Life
Published:19 Mar 2018
Special Collection: 2018 ebook collection , ECCC Environmental eBooks 1968-2022
K. Gutekunst and R. Schulz, in Microalgal Hydrogen Production: Achievements and Perspectives, ed. M. Seibert and G. Torzillo, The Royal Society of Chemistry, 2018, pp. 107-138.
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Hydrogen (H2) probably played a central role as an electron donor for the fixation of inorganic carbon at the advent of life on Earth. LUCA, the last universal common ancestor, most likely possessed a NiFe-hydrogenase and transferred the enzyme to the first bacterial and archaean cell. At present, hydrogenases are widespread in the environment and are not restricted to anoxic habitats. The occurrence of the cyanobacterial bidirectional NiFe-hydrogenase shows strong correlation with the habitat. It is prevalent in freshwater, coastal surface waters, microbial mats, and hot springs, but is absent from the open ocean and terrestrial deserts. The enzyme is truly bidirectional, with a bias towards H2 production. In the presence of oxygen, it forms two inactive states that require reactivation at distinct redox potentials. The physiology of cyanobacterial H2 production by means of the bidirectional NiFe-hydrogenases is discussed at the onset of illumination and under fermentative conditions. Approaches to enhance cyanobacterial H2 production based on the current knowledge are suggested.