title: Inhibition of denitrification activity but not of mRNA induction in Paracoccus denitrificans by nitrite at a suboptimal pH.
abstract: The influence of pH on the denitrification activity of a continuous culture of Paracoccus denitrificans was studied in relation to the presence of nitrite. After a transition from aerobic to anaerobic conditions at the suboptimal pH of 6.8, P. denitrificans was not able to build up a functional denitrification pathway. Nitrite accumulated in the medium as the predominant denitrification product. Although the nitrite reductase gene was induced properly, the enzyme could not be detected at sufficient amounts in the culture. These observations was somehow inhibited, or once synthesized nitrite reductase was inactivated, possibly by the high concentrations of nitrous acid (HNO2). Interestingly, when a P. denitrificans culture which was grown to steady-state under anaerobic conditions was then exposed to suboptimal pHs, cells exhibited a reduced overall denitrification activity, but neither nitrite nor any other denitrification intermediate accumulated.
authors.affiliation: Swiss Federal Institute for Environmental Science and Technology (EAWAG), Dübendorf, Switzerland.
authors.forename: B
authors.initials: B
authors.lastname: Baumann
authors.forename: J R
authors.initials: JR
authors.lastname: van der Meer
authors.forename: M
authors.initials: M
authors.lastname: Snozzi
authors.forename: A J
authors.initials: AJ
authors.lastname: Zehnder
mesh_terms: D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000032:analysis / Q000037:antagonists & inhibitors; D006863:Hydrogen-Ion Concentration; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009572:Nitrite Reductases / Q000037:antagonists & inhibitors; D009573:Nitrites / Q000494:pharmacology*; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010231:Paracoccus denitrificans / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; D009569:Nitric Oxide; D009572:Nitrite Reductases; D009609:Nitrous Oxide; D009584:Nitrogen