Identification of an assimilatory nitrate reductase in mutants of Paracoccus denitrificans GB17 deficient in nitrate respiration

H J Sears, Alexander G. Little, S, Richardson, B C Berks, S Spiro, N.S. Ferguson

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A Paracoccus denitrificans strain (M6Omega) unable to use nitrate as a terminal electron acceptor was constructed by insertional inactivation of the periplasmic and membrane-bound nitrate reductases. The mutant strain was able to grow aerobically with nitrate as the sole nitrogen source. It also grew anaerobically with nitrate as sole nitrogen source when nitrous oxide was provided as a respiratory electron acceptor. These growth characteristics are attributed to the presence of a third, assimilatory nitrate reductase. Nitrate reductase activity was detectable in intact cells and soluble fractions using nonphysiological electron donors. The enzyme activity was not detectable when ammonium was included in the growth medium. The results provide an unequivocal demonstration that P. denitrificans can express an assimilatory nitrate reductase in addition to the well-characterised periplasmic and membrane-bound nitrate reductases.

Original languageEnglish
Pages (from-to)61-66
Number of pages6
JournalArchives of Microbiology
Volume167
Issue number1
DOIs
Publication statusPublished - 29 Jan 1997

Keywords

  • Nitrate assimilation
  • Nitrate reductase
  • Paracoccus denitrificans
  • Thiosphaera pantotropha

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