hydrogen bacteria[′hī·drə·jən bak′tir·ē·ə]
bacteria that oxidize hydrogen and use the resulting energy to assimilate carbon. Oxidation proceeds in accordance with the formula: 2H2 + O2 = 2H2O + 138 calories. All the hydrogen bacteria are aerobes—that is, they develop only in the presence of oxygen. Because of the ability of hydrogen bacteria to synthesize organic matter from carbon dioxide, they grow well on mineral media but can also grow on meat-peptone agar and other nutrient media. Hence they are mixotrophic organisms. The ability to oxidize hydrogen is found in various taxonomic groups of bacteria. Hydrogenomonas eutropha, the most studied hydrogen bacteria, is widespread in soil; it is a small, nonsporulating, motile, flagellate rod that forms smooth, yellow, shiny colonies. In oxidizing hydrogen, hydrogen bacteria consume less oxygen than is released during the electrolysis of water. Therefore, the apparatus in which hydrogen bacteria are grown have been suggested for the regeneration of air in spacecraft. At the same time, the bacteria can be used as a source of protein.
A. A. IMSHENETSKII