Environmental Engineering Reference
TABLE 4.8 Classification of Hydrogenases
Source : Reproduced with permission from Das et al. .
dependent upon the presence of a hydrogen-producing enzyme. Hydroge-
nases and nitrogenases are the known enzymes which catalyze biological
hydrogen production. Hydrogenases are the key enzymes for the biological
hydrogen production, which can be classified as uptake hydrogenases and
reversible hydrogenases. Uptake hydrogenases, such as Ni-Fe hydrogenases
and Ni-Fe-Se hydrogenases, act as important catalysts for hydrogen con-
sumption as follows :
Reversible hydrogenases, as indicated by its name, have the ability to
produce H 2 as well as consume H 2 depending on the reaction condition,
Despite increasingly conspicuous diversity in many respects, hydrogenase
can be classified broadly into three distinct classes: Ni-Fe hydrogenase,
Fe-hydrogenase, and metal-free hydrogenase . Classification of hydrog-
enases is given in Table 4.8.
4.4.1 Biophotolysis of Water Using Microalgae
Biophotolysis is the action of light on biological systems that results in the
dissociation of a substrate usually water into molecular hydrogen and oxygen.
Photosynthetic bacteria (e.g., Rhodobactor) can use broad organic substrates,
including lactic and acetic acids, as the energy and carbon source under light