{"response":{"status":"ok","message_type":"publication"},"id":4074,"citation":"Kobayashi et al., 2025, The ISME Journal","doi":"10.1093/ismejo/wraf115","url":"https://api.seqco.de/v1/publications/4074.json","link_ext":"https://doi.org/10.1093/ismejo/wraf115","title":"Oxygen isotope fractionation during anaerobic ammonium oxidation by the marine representative \u003ci\u003eCandidatus\u003c/i\u003e Scalindua sp.","journal":"The ISME Journal","journal_loc":"19 (1)","journal_date":"2025-01-02","pub_type":"journal-article","abstract":"\u003cjats:title\u003eAbstract\u003c/jats:title\u003e\n               \u003cjats:p\u003eAnalysing the nitrogen (15ε) and oxygen (18ε) isotope effects of anaerobic ammonium oxidation (anammox) is essential for accurately assessing its potential contribution to fixed-N losses in the ocean, yet the 18ε of anammox remains unexplored. Here, we determined the previously unexplored 18ε of anammox using a highly enriched culture of the marine anammox species “Ca. Scalindua sp”. Because Scalindua significantly accelerated oxygen isotope exchange between NO2− and H2O, we introduced a new rate constant for anammox-mediated oxygen isotope exchange (keq, AMX = 8.44 ~ 13.56 × 10−2 h−1), which is substantially faster than abiotic oxygen isotope exchange (keq, abio = 1.13 × 10−2 h−1), into a numerical model to estimate the 18ε during anammox. Based on our experimental results, we successfully determined the 18ε associated with: (1) conversion of NO2− to N2 (18εNO2- → N2 = 10.6 ~ 16.1‰), (2) NO2− oxidation to NO3− (18εNO2- → NO3- = −2.9 ~ −11.0‰, inverse fractionation), (3) incorporation of oxygen from water during NO2− oxidation to NO3− (18εH2O = 16.4 ~ 19.2‰). Our study underscores the possibility that unique anammox oxygen isotope signals may be masked due to substantial anammox-mediated oxygen isotope exchange between NO2− and H2O. Therefore, careful consideration is required when utilizing δ18ONO3- and δ18ONO2- as geochemical markers to assess the potential contribution of anammox to fixed-N losses in the ocean.\u003c/jats:p\u003e","long_citation_html":"Kobayashi et al. (2025). Oxygen isotope fractionation during anaerobic ammonium oxidation by the marine representative \u003ci\u003eCandidatus\u003c/i\u003e Scalindua sp. \n\u003ci\u003eThe ISME Journal\u003c/i\u003e. \u003ca href=\"https://doi.org/10.1093/ismejo/wraf115\" target=\"_blank\"\u003eDOI:10.1093/ismejo/wraf115\u003c/a\u003e\n","created_at":"2025-06-03T22:00:23.209Z","updated_at":"2025-11-06T11:18:14.238Z","authors":[{"id":8097,"given":"Kanae","family":"Kobayashi","created_at":"2020-12-14T19:09:23.967Z","updated_at":"2020-12-14T19:09:23.967Z","url":"https://api.seqco.de/v1/authors/8097.json"},{"id":16095,"given":"Kazuya","family":"Nishina","created_at":"2025-06-03T22:00:23.238Z","updated_at":"2025-06-03T22:00:23.238Z","url":"https://api.seqco.de/v1/authors/16095.json"},{"id":16096,"given":"Keitaro","family":"Fukushima","created_at":"2025-06-03T22:00:23.246Z","updated_at":"2025-06-03T22:00:23.246Z","url":"https://api.seqco.de/v1/authors/16096.json"},{"id":16097,"given":"Yuji","family":"Onishi","created_at":"2025-06-03T22:00:23.251Z","updated_at":"2025-06-03T22:00:23.251Z","url":"https://api.seqco.de/v1/authors/16097.json"},{"id":16098,"given":"Akiko","family":"Makabe","created_at":"2025-06-03T22:00:23.256Z","updated_at":"2025-06-03T22:00:23.256Z","url":"https://api.seqco.de/v1/authors/16098.json"},{"id":1925,"given":"Mamoru","family":"Oshiki","created_at":"2019-04-15T18:47:02.306Z","updated_at":"2019-04-15T18:47:02.306Z","url":"https://api.seqco.de/v1/authors/1925.json"},{"id":16099,"given":"Keisuke","family":"Koba","created_at":"2025-06-03T22:00:23.266Z","updated_at":"2025-06-03T22:00:23.266Z","url":"https://api.seqco.de/v1/authors/16099.json"},{"id":1934,"given":"Satoshi","family":"Okabe","created_at":"2019-04-15T18:47:02.489Z","updated_at":"2019-04-15T18:47:02.489Z","url":"https://api.seqco.de/v1/authors/1934.json"}],"names":[{"id":80,"name":"Candidatus Scalindua","url":"https://api.seqco.de/v1/names/80.json","uri":"https://seqco.de/i:80"}],"subjects":[]}