Dual nitrogen and oxygen isotope fractionation during anaerobic ammonium oxidation by anammox bacteria

• Published in: The ISME Journal Vol. 13; no. 10; pp. 2426 - 2436
• Main Authors: Kobayashi, Kanae, Makabe, Akiko, Yano, Midori, Oshiki, Mamoru, Kindaichi, Tomonori, Casciotti, Karen L., Okabe, Satoshi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-10-2019; Nature Publishing Group
• Subjects: 631/326; 704/158/855; Ammonia-oxidizing bacteria; Ammonium; Ammonium Compounds - metabolism; Anaerobiosis; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Biomedical and Life Sciences; Ecology; Evolutionary Biology; Fractionation; Isotope fractionation; Isotopes; Life Sciences; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Natural environment; Nitrite reductase; Nitrogen; Nitrogen dioxide; Nitrogen Isotopes - analysis; Nitrogen Isotopes - metabolism; Oxidation; Oxidation-Reduction; Oxygen; Oxygen isotopes; Oxygen Isotopes - analysis; Oxygen Isotopes - metabolism; Reductases; Reoxidation; Species; Tracers
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/s41396-019-0440-x

Natural abundance of stable nitrogen (N) and oxygen (O) isotopes are invaluable biogeochemical tracers for assessing the N transformations in the environment. To fully exploit these tracers, the N and O isotope effects (
15
ε and
18
ε) associated with the respective nitrogen transformation processes must be known. However, the N and O isotope effects of anaerobic ammonium oxidation (anammox), one of the major fixed N sinks and NO
3
−
producers, are not well known. Here, we report the dual N and O isotope effects associated with anammox by three different anammox bacteria including “
Ca
.
Scalindua japonica
”, a putative marine species, which were measured in continuous enrichment culture experiments. All three anammox species yielded similar N isotope effects of NH
4
+
oxidation to N
2
(
15
ε
NH4→N2
) ranging from 30.9‰ to 32.7‰ and inverse kinetic isotope effects of NO
2
−
oxidation to NO
3
−
(
15
ε
NO2→NO3
 = −45.3‰ to −30.1‰). In contrast,
15
ε
NO2→N2
(NO
2
−
reduction to N
2
) were significantly different among three species, which is probably because individual anammox bacteria species might possess different types of nitrite reductase. We also report the combined O isotope effects for NO
2
−
oxidation (
18
E
NO2→NO3
) by anammox bacteria. These obtained dual N and O isotopic effects could provide significant insights into the contribution of anammox bacteria to the fixed N loss and NO
2
−
reoxidation (N recycling) in various natural environments.