Indian Journal of Microbiology

  • Year: 2005
  • Volume: 45
  • Issue: 3

Do rhizobial denitrification and nitrate ammonification act as counteracting tools for nitrate dependent inhibition of dinitrogen fixation

  • Author:
  • Gero Benckiser1, Heinz Schneider1, M. Sahul Hameed, D. Balachandar
  • Total Page Count: 9
  • DOI:
  • Page Number: 195 to 203

1Institute of Applied Microbiology, Justus Liebig University, Heinrich Buff Ring 26–32, 35392 Giessen, Germany

Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore 641 003, Tamil Nadu, India

Abstract

For evaluating how diazotrophic bacterium, Rhizobium reacts to the presence of nitrate in nodule-sphere of a legume, 3 isolates from groundnut and soybean were screened for their potential to reduce NO3−. Sequencing of 16S rDNA gene and phylogenetic analysis of the isolates showed affiliation to Agrobacterium radiobacter and A. tumefaciens. Among the strains, TNAU 14 isolated from groundnut had higher denitrification potential in the presence of C2H2. In presence of 20% (v/v) C2H2, maximum N2O formation was observed in TNAU 14, grown in GSXAMK broth. This isolate had the ability not only to reduce NO3− to N2O and N2 but also to ammonium in KNO3 mannitol medium. In the presence of acetylene (1% v/v), the nitrate ammonification by TNAU 14 was completely inhibited leading to no ammonium ion accumulation in the medium.

Keywords

Acetylene reduction, denitrification, dinitrogen fixation, nitrate ammonification