Anaerobic ammonium oxidation coupled to arsenate reduction, a novel biogeochemical process observed in arsenic-contaminated paddy soil

Miaomiao Zhang, Max Kolton, Max M. Häggblom, Xiaoxu Sun, Ke Yu, Bin He, Zaijian Yuan, Yiran Dong, Xianfa Su, Zhenyu Chen, Hui Li, Tangfu Xiao, Enzong Xiao, Weimin Sun

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Anaerobic ammonium oxidation represents an important pathway of N loss, which can be coupled with reduction of nitrite and metal(loid)s (e.g., Fe(III) and Mn(IV)). Similar to Fe(III) and Mn(IV), As(V) is also an active metal(loid) and ammonium oxidation coupled with As(V) reduction is thermodynamically feasible. However, little is known about this potential process. In this study, anaerobic ammonium oxidation coupled with As(V) reduction, designated as Asammox, was observed in cultures inoculated from As-contaminated paddy soil using 15N isotope tracer analysis. Compared with the treatment amended with 15N-urea only, the production of 15N-labeled N2 (i.e., 30N2 and 29N2) was significantly greater in the treatment amended with As(V) and 15N-urea. Furthermore, the abundances of the genes encoding for arsenate reductase (arrA) and hydrazine synthase (hzsB) were significantly higher in the treatment amended with As(V) and 15N-urea than those in the treatment amended with 15N-urea only. In addition, putative Asammox bacteria affiliated with Halomonas, Pelagibacterium, and Chelativorans were identified by DNA-stable isotope probing. Members of Ca. Brocadia were the most dominant Anammox bacteria in the soil cultures and may interact with Asammox bacteria in ammonium oxidation, suggesting that the N loss may be attributed to the contribution of Asammox and Anammox in the As-contaminated soil. The observation of Asammox, a novel biogeochemical process, and identification of bacteria responsible for this biogeochemical process expands the fundamental understanding of both N and As biogeochemical cycling. In addition, this study provides a proof-of-concept for investigating anaerobic ammonium oxidation coupled with metal(loid)s reduction by combining stable isotope probing and isotope tracer microcosm incubations.

Original languageEnglish
Pages (from-to)11-22
Number of pages12
JournalGeochimica et Cosmochimica Acta
Volume335
DOIs
StatePublished - 15 Oct 2022

Keywords

  • Anaerobic ammonium oxidation
  • Arsenate reduction
  • As-contaminated paddy soil
  • Halomonas
  • hzsB gene

ASJC Scopus subject areas

  • Geochemistry and Petrology

Fingerprint

Dive into the research topics of 'Anaerobic ammonium oxidation coupled to arsenate reduction, a novel biogeochemical process observed in arsenic-contaminated paddy soil'. Together they form a unique fingerprint.

Cite this