title: Symbiotic Bradyrhizobium japonicum reduces N2O surrounding the soybean root system via nitrous oxide reductase.
abstract: N(2)O reductase activity in soybean nodules formed with Bradyrhizobium japonicum was evaluated from N(2)O uptake and conversion of (15)N-N(2)O into (15)N-N(2). Free-living cells of USDA110 showed N(2)O reductase activity, whereas a nosZ mutant did not. Complementation of the nosZ mutant with two cosmids containing the nosRZDFYLX genes of B. japonicum USDA110 restored the N(2)O reductase activity. When detached soybean nodules formed with USDA110 were fed with (15)N-N(2)O, they rapidly emitted (15)N-N(2) outside the nodules at a ratio of 98.5% of (15)N-N(2)O uptake, but nodules inoculated with the nosZ mutant did not. Surprisingly, N(2)O uptake by soybean roots nodulated with USDA110 was observed even in ambient air containing a low concentration of N(2)O (0.34 ppm). These results indicate that the conversion of N(2)O to N(2) depends exclusively on the respiratory N(2)O reductase and that soybean roots nodulated with B. japonicum carrying the nos genes are able to remove very low concentrations of N(2)O.
authors.affiliation: Graduate School of Life Sciences, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Sameshima-Saito
authors.forename: Kaori
authors.initials: K
authors.lastname: Chiba
authors.forename: Junta
authors.initials: J
authors.lastname: Hirayama
authors.forename: Manabu
authors.initials: M
authors.lastname: Itakura
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Mitsui
authors.forename: Shima
authors.initials: S
authors.lastname: Eda
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Minamisawa
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D020369:Bradyrhizobium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D009586:Nitrogen Fixation; D009609:Nitrous Oxide / Q000378:metabolism*; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology*; D013025:Glycine max / Q000254:growth & development / Q000382:microbiology*; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D010088:Oxidoreductases; C022763:nitrous oxide reductase; D009609:Nitrous Oxide