Nitrate respiratory metabolism in an obligately autotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6

Arch Microbiol. 2001 Jan;175(1):75-8. doi: 10.1007/s002030000230.


Hydrogenobacter thermophilus strain TK-6 was observed to grow anaerobically on nitrate as an electron acceptor when molecular hydrogen was used as an energy source. Nitrite was detected as the product of a respiratory reaction. 15NO, 15N2O, and 15N2 were detected with Na15NO3 as an electron acceptor. Western immunoblot analysis showed that cell-free extracts from cells grown on nitrate reacted with antibodies against heme cd1-type nitrite reductase from Pseudomonas aeruginosa. The positive bands, which had molecular masses similar to that of the heme cd1-type nitrite reductase, were also stained by heme staining. These results indicate that nitrite reductase of strain TK-6 is a heme cd1-type enzyme. Activity of ATP:citrate lyase, one of the key enzymes of the reductive TCA cycle, was detected in cell-free extract of cells cultivated on nitrate, which indicates that the cycle operates during anaerobic growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Anaerobiosis
  • Bacteria, Aerobic / growth & development
  • Bacteria, Aerobic / metabolism*
  • Blotting, Western
  • Cytochromes
  • Electron Transport Complex IV / analysis
  • Heme / analysis
  • Multienzyme Complexes / metabolism
  • Nitrates / metabolism*
  • Nitrite Reductases / analysis
  • Oxo-Acid-Lyases / metabolism


  • Cytochromes
  • Multienzyme Complexes
  • Nitrates
  • Heme
  • Adenosine Triphosphate
  • Nitrite Reductases
  • nitrite reductase (NO-forming)
  • Electron Transport Complex IV
  • Oxo-Acid-Lyases
  • citrate (pro-3S)-lyase