Nitrous oxide emission potentials of Burkholderiaspecies isolated from the leaves of a boreal peat moss Sphagnum fuscum

Using a culture-based nitrous oxide (N2O) emission assay, three active N2O emitters were isolated from Sphagnum fuscumleaves and all identified as members of Burkholderia. These isolates showed N2O emission in the medium supplemented with but not with , and Burkholderiasp. SF-E2 showed the most efficient N2O emission (0.20 μg·vial−1·day−1) at 1.0 mM KNO3. In Burkholderiasp. SF-E2, the optimum pH for N2O production was 5.0, close to that of the phyllosphere of Sphagnummosses, while the optimum temperature was uniquely over 30 °C. The stimulating effect of additional 1.5 mM sucrose on N2O emission was ignorable, but Burkholderiasp.SF-E2 upon exposure to 100 mg·L−1E-caffeic acid showed uniquely 67-fold higher N2O emission. All of the three N2O emitters were negative in both acetylene inhibition assay and PCR assay for nosZ-detection, suggesting that N2O reductase or the gene itself is missing in the N2O-emitting Burkholderia.