Characterization of a spontaneous mutant of Azotobacter vinelandii in which vanadium-dependent nitrogen fixation is not inhibited by molybdenum

Umesh K. Bageshwar, Ramesh Raina, H. K. Das

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

A spontaneous mutant derivative of Azotobacter vinelandii CA12 (ΔnifHDK), in which vanadium-dependent nitrogen fixation is not inhibited by molybdenum (A. vinelandii CARR), grows profusely on BNF-agar containing 1 μM Na2MoO4, alone or supplemented with 1 μM V2O5. The expression of A. vinelandii vnfH :: lacZ and vnfA :: lacZ fusions in A. vinelandii CARR was not inhibited by 1 mM Na2MoO4, whereas molybdenum at much lower concentration inhibited the expression of vnfH :: lacZ and vnfA :: lacZ fusions in A. vinelandii CA12. The mutant also exhibited normal acetylene reduction activity in the presence of 1 μM Na2MoO4. The expression of A. vinelandii nifH :: lacZ fusion in A. vinelandii CARR was low even though the cells were cultured under non-repressing conditions with urea as nitrogen source in the presence of Na2MoO4. The molybdenum content of A. vinelandii CARR cells was found to be about one-fourth that of A. vinelandii CA12. No nitrate reductase activity could be detected in A. vinelandii CARR when the cells were cultured in the presence of 10 μM Na2MoO4, whereas A. vinelandii CA12 exhibited some activity even with 100 pM Na2MoO4.

Original languageEnglish (US)
Pages (from-to)161-167
Number of pages7
JournalFEMS Microbiology Letters
Volume162
Issue number1
DOIs
StatePublished - May 1 1998
Externally publishedYes

Keywords

  • Azotobacter vinelandii
  • Nitrate reductase
  • Vanadium-dependent nitrogen fixation
  • lacZ fusion

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology
  • Genetics

Fingerprint Dive into the research topics of 'Characterization of a spontaneous mutant of Azotobacter vinelandii in which vanadium-dependent nitrogen fixation is not inhibited by molybdenum'. Together they form a unique fingerprint.

  • Cite this