The importance of hydrogen to biological systems is emphasized by its central position in the spiral periodic table. Hydrogen is a constituent of water and nearly all organic molecules. Cells use H⁺ gradients to drive ATP synthesis, solute transport, and flagella rotation. Hydrogenase enzymes (reviewed by Vignais et al, 2001) mediate the redox interconversion of H⁺ and H₂. Some aerobic (Friedrich and Schwarz, 1993) and anaerobic (Gross and Simon, 2003) chemolithotrophic prokaryotes can derive energy for growth from the oxidation of H₂, catalyzed by [NiFe]-hydrogenases. [Fe]-Hydrogenases are typically associated with the reduction of H⁺ leading to the evolution of H₂ (Frey, 2002), and are found in both prokaryotes (Nandi and Sengupta, 1998) and lower eukaryotes (some fungi, algae, and protozoa) (Horner et al, 2002). Metal-free hydrogenases have been discovered in methanogenic archaea (Berkessel, 2001).

For more information:

Search Medline for hydrogen metabolism AND bacteria