title: Analysis of nitrification in agricultural soil and improvement of nitrogen circulation with autotrophic ammonia-oxidizing bacteria.
abstract: Accumulations of inorganic nitrogen (NH₄⁺, NO₂⁻, and NO₃⁻) were analyzed to evaluate the nitrogen circulation activity in 76 agricultural soils. Accumulation of NH₄⁺ was observed, and the reaction of NH₄⁺→ NO₂⁻ appeared to be slower than that of NO₂⁻ → NO₃⁻ in agricultural soil. Two autotrophic and five heterotrophic ammonia-oxidizing bacteria (AOB) were isolated and identified from the soils, and the ammonia-oxidizing activities of the autotrophic AOB were 1.0 × 10³-1.0 × 10⁶ times higher than those of heterotrophic AOB. The relationship between AOB number, soil bacterial number, and ammonia-oxidizing activity was investigated with 30 agricultural soils. The ratio of autotrophic AOB number was 0.00032-0.26% of the total soil bacterial number. The soil samples rich in autotrophic AOB (>1.0 × 10⁴ cells/g soil) had a high nitrogen circulation activity, and additionally, the nitrogen circulation in the agricultural soil was improved by controlling the autotrophic AOBs.
authors.affiliation: Department of Biotechnology, Faculty of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 5258577, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Matsuno
authors.forename: Sachie
authors.initials: S
authors.lastname: Horii
authors.forename: Takanobu
authors.initials: T
authors.lastname: Sato
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Matsumiya
authors.forename: Motoki
authors.initials: M
authors.lastname: Kubo
mesh_terms: D000383:Agriculture; D000641:Ammonia / Q000378:metabolism*; D052818:Autotrophic Processes; D001419:Bacteria / Q000378:metabolism*; D058465:Nitrification; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D012987:Soil; D000641:Ammonia; D009584:Nitrogen