title: Nitrogen, carbon, and sulfur isotopic change during heterotrophic (Pseudomonas aureofaciens) and autotrophic (Thiobacillus denitrificans) denitrification reactions.
abstract: In batch culture experiments, we examined the isotopic change of nitrogen in nitrate (δ(15)NNO3), carbon in dissolved inorganic carbon (δ(13)CDIC), and sulfur in sulfate (δ(34)SSO4) during heterotrophic and autotrophic denitrification of two bacterial strains (Pseudomonas aureofaciens and Thiobacillus denitrificans). Heterotrophic denitrification (HD) experiments were conducted with trisodium citrate as electron donor, and autotrophic denitrification (AD) experiments were carried out with iron disulfide (FeS2) as electron donor. For heterotrophic denitrification experiments, a complete nitrate reduction was accomplished, however bacterial denitrification with T. denitrificans is a slow process in which, after seventy days nitrate was reduced to 40% of the initial concentration by denitrification. In the HD experiment, systematic change of δ(13)CDIC (from -7.7‰ to -12.2‰) with increase of DIC was observed during denitrification (enrichment factor εN was -4.7‰), suggesting the contribution of C of trisodium citrate (δ(13)C=-12.4‰). No SO4(2-) and δ(34)SSO4 changes were observed. In the AD experiment, clear fractionation of δ(13)CDIC during DIC consumption (εC=-7.8‰) and δ(34)SSO4 during sulfur use of FeS2-S (around 2‰), were confirmed through denitrification (εN=-12.5‰). Different pattern in isotopic change between HD and AD obtained on laboratory-scale are useful to recognize the type of denitrification occurring in the field.
authors.affiliation: Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan. Electronic address: hosono@kumamoto-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hosono
authors.affiliation: Priority Organization for Innovation and Excellence, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Kelly
authors.initials: K
authors.lastname: Alvarez
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Kumamoto 860-8555, Japan.
authors.forename: In-Tian
authors.initials: IT
authors.lastname: Lin
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, 2-39-1, Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Shimada
mesh_terms: D052818:Autotrophic Processes; D002244:Carbon / Q000032:analysis / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis / Q000378:metabolism; D002951:Citrates / Q000737:chemistry / Q000378:metabolism; D058440:Denitrification; D052836:Heterotrophic Processes; D007501:Iron / Q000737:chemistry; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000032:analysis / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*; D000077559:Sodium Citrate; D013431:Sulfates / Q000378:metabolism; D013440:Sulfides / Q000737:chemistry; D013455:Sulfur / Q000032:analysis / Q000378:metabolism*; D013460:Sulfur Isotopes; D013855:Thiobacillus / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D002951:Citrates; D009566:Nitrates; D009587:Nitrogen Isotopes; D013431:Sulfates; D013440:Sulfides; D013460:Sulfur Isotopes; C011342:pyrite; D000077559:Sodium Citrate; D013455:Sulfur; D002244:Carbon; D007501:Iron; D009584:Nitrogen
keywords: Autotrophic denitrification; Batch culture experiments; C, N, S isotopes; Heterotrophic denitrification; Isotope fractionation