Table 1 presents biotechnological potential of hydrogenase employing different activities of this enzyme. Besides direct application in the energy conversion systems hydrogenase is a useful tool to reduce the energy consumption and protect the environment. Actually, the ability of hydrogenase to reduce reversibly some compounds like metal ions, viologens and other electron acceptors could be applied for development of safe and convenient hydrogen energy accumulator. If this compound is well soluble in water, its concentrated solution would be an efficient H2 storage medium. Such an approach was experimentally proven using methyl viologen as a hydrogen binder and immobilized hydrogenase as a catalyst. An 0.5 M aqueous solution of MV accumulates 240 times as much H2 as pure water dissolves under the same pressure. The hydrogenase provides the charge-discharge cycle within a reasonable time ,
Hydrogen production Photocatalytic systems for H2 production. Hydrogen enzyme electrode for H2 electrosynthesis. H2 production from some metals and reduced compounds.
Hydrogen consumption Hydrogen enzyme electrode for fuel cells. Amperometric biosensor for hydrogen. Accumulator for hydrogen energy. Biosynthesis of fine chemicals. Treatment of waste water polluted by heavy metals.
Hydrogen-deuterium exchange Preparative separation of hydrogen isotopes. Detritiation of cooling water in nuclear power plants. Biosynthesis of chemicals labelled with D or T.
Different approaches for enzymatic synthesis of fine chemicals using H2 as the ultimate reducing agent were suggested , Hydrogenase and some specific enzymes, coupling via cofactors, carry out the synthesis under soft conditions. Such multi-enzyme systems for production of fine chemicals have high specificity and should consume less energy as compared with usual chemical synthesis.
High hydrogen isotopes effect of hydrogen production by T. roseopersicina was observed when the activities were determined in usual and heavy water. The rate of H2 production in H20 was approximately 5 times higher than the rate of D2 production in D20 , This effect could be applied for preparative production of heavy water and separation of hydrogen isotopes. During the long-time electrosynthesis of H2 from H20 on the hydrogenase electrode the heavy water will be accumulated in aqueous phase.
Tritium separation from hydrogen is required for detritiation of aqueous waters from nuclear power plants to avoid the environmental pollution by this radioactive isotope. Nobel metal catalysts have been traditionally employed for design of heavy water production and tritium separation systems , High activity and oxygen stability of hydrogenase from phototrophic bacteria [6,15] in hydrogen-water isotope exchange reaction gives good perspectives for application of this enzyme as a catalyst in the production of heavy water and separation of hydrogen isotopes.
The metal-reducing ability of hydrogenase may help to remediate environmental pollution by some toxic metals. Hydrogenase has a potential for biological recovery of rare and expensive metals as well. Some hydrogenase containing microorganisms and their consortia with plants could be used for metal ions biosorbtion and redox transformation , Enzymatic recovery of elemental palladium by using hydrogenase activity of sulfate-reducing bacteria was demonstrated ,
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