Sulfur-Driven Iron Reduction Coupled to Anaerobic Ammonium Oxidation

Abstract

A new biogeochemical pathway has been suggested to be present in terrestrial ecosystems, linking the nitrogen and iron cycles via ferric iron reduction coupled to anaerobic ammonium oxidation. However, the underlying microbiological process has not been demonstrated to date. Here we report a stable consortium, HJ-4, composed of Anaerospora hongkongensis (85%) and facultative anaerobe, Comamonadaceae (15%), which can process ferrihydrite reduction coupled to anaerobic ammonium oxidation driven by sulfur redox cycling. In this process, A. hongkongensis reduces elemental sulfur, sulfite, and polysulfides to sulfide, which fuels ferrihydrite reduction. Sulfide, elemental sulfur, sulfite, and polysulfides serve as electron shuttles, completing the sulfur cycle between A. hongkongensis and ferrihydrite. In addition, Comamonadaceae shows ammonium oxidation potential under aerobic conditions, with nitrite as the main product. We inferred that Comamonadaceae mediates simultaneous nitrification-denitrification coupled to iron redox cycling through nitrate/nitrite-dependent ferrous oxidation under anaerobic conditions. Hence, we discovered a novel pathway for ferric iron reduction coupled to ammonium oxidation, highlighting the key role of electron shuttles and nitrate/nitrite-dependent ferrous oxidation in this process. The biogeochemical cycling of sulfur, iron, and nitrogen could be coupled in aquatic and terrestrial ecosystems.

Analysis of viral and bacterial communities in groundwater associated with contaminated land

“…Thermoanaerobacteraceae and Caulobacteraceae have been associated with sulfate reduction (Bagi et al, 2017), and, recently, Comamonadaceae has been implicated in a new mechanism of sulfur-driven iron reduction coupled to ammonium oxidation (Bao and Li, 2017).…”

Development of a Novel Membrane‐less Microbial Fuel Cell (ML‐MFC) with a Sandwiched Nitrifying Chamber for Efficient Wastewater Treatment

“…In addition, the emergence of anaerobic bacteria revealed the presence of low DO layer in inner biofilm. For nitrogen removal, the ammonium converted into nitrite was attributed to Comamonadaceae _ unclassified (4.5 %) and Nitrosomonas (0.4 %), while the nitrite oxidizing was mainly caused by Nitrospira (1.2 %). Denitratisoma (5.6 %) is a well‐known heterotrophic denitrifying bacterium, which can use nitrate or nitrite as electron acceptor and acetate as electron donor .…”

A thermodynamic chemical reaction network drove autocatalytic prebiotic peptides formation

“…Notably, quite a few iron oxides could be abiotically reduced by sulfide generated from Sammox in an iron-rich environment, then an illusion of ferric iron reduction coupled to anaerobic ammonium oxidation (Feammox) arises [37][38][39] . Indeed, it is still unclear to what extent Sammox overlaps with Feammox; however, we can infer that Sammox may be widely distributed in different anoxic environments based on the ubiquity of Ralstonia spp.…”

“…As a self For enrichment, approximately 0.5 g of paddy soil was transferred to 100 ml of double distilled water. After shaking, five milliliters of the suspension was inoculated into 100 ml of anaerobic freshwater medium 39 Shotgun project has been deposited at DDBJ/ENA/GenBank under the accession QMKS00000000. The version described in this paper is version QMKS01000000.…”

“…The pH of the solvent was adjusted with 1.0 At each sampling time point, each serum bottle was shaken vigorously to equilibrate the N 2 between dissolved and gas phases. Dinitrogen sampling and determination was performed according to a literature procedure39 .…”