Isolation and characterization of NH4+-excreting mutants of Enterobacter gergoviae 57-7

Yong Xing Li, Yue Mei Dong, Jiu Di Li

Research output: Contribution to journalArticlepeer-review


NH4+-excreting mutants were isolated from Enterobacter gergoviae 57-7 wild type as methylamine resistant strains which were obtained by mutagenesis with a transposable element Tn5. The MG 61 mutants excreted 2 mmol/L of ammonium during a diazotrophic growth. The growth of MG 61 mutants were slower than the growth of wild types because of its excreting ammonium. MG 61 mutants expressed up to 86% of the fully depressed nitrogenase activity when grown in a medium containing 20 mmol/L ammonium. By contrast the ammonium grown cultures of wild type had no nitrogenase activity. In the presence of 5 mmol/L or 30 mmol/L of ammonium in the medium, the growth of MG 61 mutants was as same as CK and much slower than that of the wild types which means that the mutants could not utilize amonium very well in the medium. But MG 61 mutants could utilize glutamate as a sole nitrogen source. In the presence of nitrate (10 mmol/L) in the medium, MG 61 mutants grew slowly but excreted 7. 8 mmol/L of ammonium.

Original languageEnglish (US)
Pages (from-to)563-567
Number of pages5
JournalActa Botanica Sinica
Issue number7
StatePublished - Dec 1 1996
Externally publishedYes


  • Enterobacter gergoviae
  • NH-excreting mutant
  • Tn5 transposon mutagenesis methylamine

ASJC Scopus subject areas

  • Biochemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Plant Science

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