title: Influence of copper on expression of nirS, norB and nosZ and the transcription and activity of NIR, NOR and N2 OR in the denitrifying soil bacteria Pseudomonas stutzeri.
abstract: Reduction of the potent greenhouse gas nitrous oxide (N(2)O) occurs in soil environments by the action of denitrifying bacteria possessing nitrous oxide reductase (N(2)OR), a dimeric copper (Cu)-dependent enzyme producing environmentally benign dinitrogen (N(2)). We examined the effects of increasing Cu concentrations on the transcription and activity of nitrite reductase (NIR), nitric oxide reductase (NOR) and N2 OR in Pseudomonas stutzeri grown anaerobically in solution over a 10-day period. Gas samples were taken on a daily basis and after 6 days, bacterial RNA was recovered to determine the expression of nirS, norB and nosZ encoding NIR, NOR and N(2)OR respectively. Results revealed that 0.05 mM Cu caused maximum conversion of N(2)O to N(2) via bacterial reduction of N(2)O. As soluble Cu generally makes up less than 0.001% of total soil Cu, extrapolation of 0.05 mg l(-l) soluble Cu would require soils to have a total concentration of Cu in the range of, 150-200 μg g(-1) to maximize the proportion of N(2)O reduced to N(2). Given that many intensively farmed agricultural soils are deficient in Cu in terms of plant nutrition, providing a sufficient concentration of biologically accessible Cu could provide a potentially useful microbial-based strategy of reducing agricultural N(2)O emissions.
authors.affiliation: Bio Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, Christchurch, 7647, New Zealand.
authors.forename: Amanda
authors.initials: A
authors.lastname: Black
authors.affiliation: Bio Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, Christchurch, 7647, New Zealand.
authors.forename: Pei-Chun L
authors.initials: PC
authors.lastname: Hsu
authors.affiliation: Bio Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, Christchurch, 7647, New Zealand.|Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Hamonts
authors.affiliation: Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Lincoln, Christchurch, 7647, New Zealand.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Clough
authors.affiliation: Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Lincoln, Christchurch, 7647, New Zealand.
authors.forename: Leo M
authors.initials: LM
authors.lastname: Condron
mesh_terms: D000693:Anaerobiosis; D003067:Coenzymes / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D058440:Denitrification; D009572:Nitrite Reductases / Q000096:biosynthesis / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism; D010088:Oxidoreductases / Q000096:biosynthesis / Q000378:metabolism*; D044223:Pseudomonas stutzeri / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D003067:Coenzymes; D003300:Copper; D010088:Oxidoreductases; D009572:Nitrite Reductases; C022763:nitrous oxide reductase; C034747:nitric-oxide reductase; D009609:Nitrous Oxide; D009584:Nitrogen