Disruption of narG, the Gene Encoding the Catalytic Subunit of Respiratory Nitrate Reductase, Also Affects Nitrite Respiration in Pseudomonas fluorescens YT101 |
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Authors: | Jean-Franois Ghiglione Laurent Philippot Philippe Normand Robert Lensi and Patrick Potier |
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Institution: | Laboratoire d'Ecologie Microbienne du Sol, UMR C.N.R.S. 5557, Université Claude Bernard, Lyon 1, 69622 Villeurbanne Cedex, France. |
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Abstract: | The Pseudomonas fluorescens YT101 gene narG, which encodes the catalytic alpha subunit of the respiratory nitrate reductase, was disrupted by insertion of a gentamicin resistance cassette. In the Nar(-) mutants, nitrate reductase activity was not detectable under all the conditions tested, suggesting that P. fluorescens YT101 contains only one membrane-bound nitrate reductase and no periplasmic nitrate reductase. Whereas N(2)O respiration was not affected, anaerobic growth with NO(2) as the sole electron acceptor was delayed for all of the Nar(-) mutants following a transfer from oxic to anoxic conditions. These results provide the first demonstration of a regulatory link between nitrate and nitrite respiration in the denitrifying pathway. |
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