Growth of Spirillum lipoferum at constant partial pressures of oxygen, and the properties of its nitrogenase in cell-free extracts

J Gen Microbiol. 1977 Jan;98(1):87-93. doi: 10.1099/00221287-98-1-87.

Abstract

Spirillum lipoferum, an N2-fixing organism, was grown at constant concentrations of dissolved O2. When supplied with NH4+ aerobically, its doubling time was 1 h; when it fixed N2 microaerophilically, its doubling time was 5-5 to 7 h and the optimal PO2 for growth was 0-005 to 0-007 atm. At its optimal PO2 for growth on N2, S. lipoferum assimilated 8 to 10 mg nitrogen/g carbon substrate used; its efficiency was less at higher PO2 levels. Nitrogenase in cell-free extracts required Mg2+ and Mn2+, and the Fe-protein was activated by Rhodospirillum rubrum activating factor. The nitrogenase had an optimal pH of 7-1 to 7-4 and an apparent Km for acetylene of 0-0036 atm. Extracts of S. lipoferum lost their nitrogenase activity on storage at -18 degrees C, and activity was restored by adding purified Fe-protein from other N2-fixing bacteria.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylene / metabolism
  • Ammonium Chloride / metabolism
  • Bacterial Proteins / pharmacology
  • Cell-Free System
  • Enzyme Activation
  • Hydrogen-Ion Concentration
  • Nitrogen Fixation
  • Nitrogenase / metabolism*
  • Oxidation-Reduction
  • Oxygen*
  • Partial Pressure
  • Spirillum / enzymology
  • Spirillum / growth & development*
  • Temperature

Substances

  • Bacterial Proteins
  • Ammonium Chloride
  • Nitrogenase
  • Acetylene
  • Oxygen