Denitrifying enzyme synthesis and activity was studied in Achromobacter cycloclastes. Nitrite and nitrous oxide reductases were synthesized in response to anaerobiosis in the absence of nitrogenous oxides, but synthesis was promoted when a nitrogenous oxide was present. Nitrite reductase synthesis was promoted by NO3- and NO2-, while N2O reductase synthesis was promoted by NO2- and N2O. In continuous culture at dissolved O2 concentrations ranging from air saturation to complete anaerobiosis, NO3- and N2O reductase proteins were synthesized at all O2 concentrations. Full induction occurred when dissolved O2 concentrations fell below 2 μM. Nitrate reductase activity was present at all O2 concentrations, but the N2O reductase protein was not active until O2 concentrations were decreased to 23 μM. Nitrite reduction was the most O2-sensitive denitrifying step. Synthesis did not occur until dissolved O2 was below 2 μM. The same pattern was observed for NO-reducing activity. The synthesis of the suite of denitrifying enzymes was not uniformly regulated by particular nitrogenous oxides as inducers, nor by similar O2 concentrations. Because of the stringent control by O2 on NO2- reductase synthesis, complete denitrification in this organism could not occur until O2 concentrations were very low, approximately 2 μM (64 μg O2 l-1).
|Number of pages||8|
|Journal||FEMS Microbiology Letters|
|State||Published - Apr 1990|
Bibliographical noteFunding Information:
We thank C. Hulse and B. Averill for providing purified NO 2-and N20 reduetase, A. Arun-akumari for assistan~ in producing antisera, and J, Wildenthal for excellent technical assistance, This work was supported by research gt~mt No. CHE-8607681 from the U.S. National Science Foundation and the Michigan Agricultural Experiment Station. Support for M.S,C. was also provided by a fellowship from the USDA National Needs in Bioteelmology Program.
- Nitrite reductase
- Nitrous oxide reductase
- Oxygen regulation
ASJC Scopus subject areas
- Molecular Biology