Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Reduction of nitrate in Shewanella

Journal Article · · The ISME Journal: Multidisciplinary Journal of Microbial Ecology
 [1];  [2];  [3];  [4];  [5];  [4];  [6];  [1]
  1. University of Oklahoma
  2. ORNL
  3. University of Oklahoma, Norman
  4. Pacific Northwest National Laboratory (PNNL)
  5. University of Southern California
  6. Michigan State University, East Lansing
In the genome of Shewanella oneidensis, a napDAGHB gene cluster encoding periplasmic nitrate reductase (NapA) and accessory proteins and an nrfA gene encoding periplasmic nitrite reductase (NrfA) have been identified. These two systems seem to be atypical because the genome lacks genes encoding cytoplasmic membrane electron transport proteins, NapC for NAP and NrfBCD/NrfH for NRF, respectively. Here, we present evidence that reduction of nitrate to ammonium in S. oneidensis is carried out by these atypical systems in a two-step manner. Transcriptional and mutational analyses suggest that CymA, a cytoplasmic membrane electron transport protein, is likely to be the functional replacement of both NapC and NrfH in S. oneidensis. Surprisingly, a strain devoid of napB encoding the small subunit of nitrate reductase exhibited the maximum cell density sooner than the wild type. Further characterization of this strain showed that nitrite was not detected as a free intermediate in its culture and NapB provides a fitness gain for S. oneidensis to compete for nitrate in the environments. On the basis results from mutational analyses of napA, napB, nrfA and napBnrfA in-frame deletion mutants, we propose that NapB is able to favor nitrate reduction by routing electrons to NapA exclusively.
Research Organization:
Oak Ridge National Laboratory (ORNL)
Sponsoring Organization:
SC USDOE - Office of Science (SC)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
963710
Journal Information:
The ISME Journal: Multidisciplinary Journal of Microbial Ecology, Journal Name: The ISME Journal: Multidisciplinary Journal of Microbial Ecology Journal Issue: 1751-736 Vol. 3
Country of Publication:
United States
Language:
English