title: Phylogenetic and functional diversity of denitrifying bacteria isolated from various rice paddy and rice-soybean rotation fields.
abstract: Denitrifiers can produce and consume nitrous oxide (N(2)O). While little N(2)O is emitted from rice paddy soil, the same soil produces N(2)O when the land is drained and used for upland crop cultivation. In this study, we collected soils from two types of fields each at three locations in Japan; one type of field had been used for continuous cultivation of rice and the other for rotational cultivation of rice and soybean. Active denitrifiers were isolated from these soils using a functional single-cell isolation method, and their taxonomy and denitrifying properties were examined. A total of 110 denitrifiers were obtained, including those previously detected by a culture-independent analysis. Strains belonging to the genus Pseudogulbenkiania were dominant at all locations, suggesting that Pseudogulbenkiania denitrifiers are ubiquitous in various rice paddy soils. Potential denitrifying activity was similar among the strains, regardless of the differences in taxonomic position and soil of origin. However, relative amounts of N(2) in denitrification end products varied among strains isolated from different locations. Our results also showed that crop rotation had minimal impact on the functional diversity of the denitrifying strains. These results indicate that soil and other environmental factors, excluding cropping systems, could select for N(2)-producing denitrifiers.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1–1–1 Yayoi, Bunkyo-ku, Tokyo 113–8657, Japan. kanakotago@yahoo.co.jp
authors.forename: Kanako
authors.initials: K
authors.lastname: Tago
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishii
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Nishizawa
authors.forename: Shigeto
authors.initials: S
authors.lastname: Otsuka
authors.forename: Keishi
authors.initials: K
authors.lastname: Senoo
mesh_terms: D000383:Agriculture; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D044822:Biodiversity; D058440:Denitrification; D007564:Japan; D008969:Molecular Sequence Data; D009609:Nitrous Oxide / Q000378:metabolism; D012275:Oryza / Q000254:growth & development; D010802:Phylogeny; D012988:Soil Microbiology; D013025:Glycine max / Q000254:growth & development
chemical_list: D009609:Nitrous Oxide