Nitrate reductase (Nar) of F. canadensis is membrane-bound. Glucose is the most effective reductant to support nitrate uptake, and methyl and benzyl viologens are good electron donors to Nar both in intact cells and in membrane fractions. Nitrate uptake depends upon nitrate reduction, and requires the presence of active Nar. Nitrate transport depends upon the transmembrane pH gradient. / Oxygen reversibly inhibits nitrate uptake, and the minimal air saturation for this inhibition is about 2-4%. Oxygen inhibits denitrification at the level of nitrate transport rather than its reduction. The reduction of both nitric oxide (NO) and nitrous oxide by F. canadensis is relatively tolerant to oxygen, and its nitrite reductase (Nir) is much more sensitive to oxygen than the other reductases. Neither copper- nor heme-type Nir DNA probes from Pseudomonas species hybridized with the total DNA of F. canadensis, indicating that F. canadensis Nir may possess unique properties. / F. canadensis keeps the NO concentration very low under normal conditions. However, ionophores (carbonyl cyanide m-chlorophenylhydrazone (CCCP), carbonyl cyanide p-trifluoromethoxylphenylhydrazone (FCCP), and nigericin), high concentrations of nitrite, and low pH stimulate net NO production during reduction of nitrite. NO consumption by F. canadensis inhibited by several inhibitors. They are azide, cyanide, CCCP, FCCP, nigericin, sulfide, hydroxylamine, carbon monoxide, diethyldithiocarbamate, and Triton X-100. NO is toxic to Nor (nitric oxide reductase) only at concentrations $>$67 nM. / Studies on chloramphenicol inhibition of denitrification enzyme activity indicate that chloramphenicol inhibits denitrification at the levels of nitrate reduction and NO consumption in F. canadensis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28962 |
| Date | January 1995 |
| Creators | Wu, Qitu |
| Contributors | Knowles, Roger (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Natural Resource Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001467867, proquestno: NN05814, Theses scanned by UMI/ProQuest. |
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