A laboratory-scale anammox granular-sludge bioreactor community reconstructed with genome-centric metagenomics and metatranscriptomics. Brocadia-affiliated anammox bacteria dominate nitrogen removal, while Chlorobi-affiliated and other heterotrophic bacteria recycle nitrate to nitrite, degrade EPS-derived peptides, and scavenge detrital products from anammox growth.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Brocadia-affiliated anammox bacterium AMX1 — ontology label: Candidatus Brocadia sinica | NCBITaxon:795830 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
CROSS_FEEDER
|
N/A |
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| Chlorobi-affiliated heterotrophic bacteria — ontology label: Chlorobiota | NCBITaxon:1090 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
CROSS_FEEDER
|
N/A |
|
|||
| anammox-granule heterotrophic flanking bacteria — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
SECONDARY_FERMENTER
CROSS_FEEDER
|
N/A |
|
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Ecological Interactions
The graph shows only explicitly linked interaction participants. Community members without an asserted participant link are omitted; membership alone does not imply an interaction.
Anammox Ammonium-Nitrite Conversion
The Brocadia-affiliated AMX1 genome expressed anammox genes in the nitrogen-removing granule reactor. This supports active metabolic potential; the proposed transfers to neighboring heterotrophs were inferred from genomes and transcripts rather than measured as partner-resolved fluxes.
Participating Taxa: Brocadia-affiliated anammox bacterium AMX1
Metabolites: ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech), nitrite (CHEBI:16301 · MediaIngredientMech · CMMMech)
HYPOTHESIZED - anammox-derived nitrate could supply heterotrophic nitrate reduction and a nitrite-return loop; expression supports potential but not the exchanged flux.
HYPOTHESIZED - anammox-associated extracellular material could feed heterotrophic proteolysis; the source of consumed protein and the transfer were not traced in this study.
HYPOTHESIZED - biomass turnover or released small substrates could feed heterotrophs; wastewater-derived organic carbon and unresolved pathway directions prevent exclusive attribution to AMX1.
Evidence
-
doi:10.1038/ncomms15416 - SUPPORT (COMPUTATIONAL)"genes involved in anammox metabolism"
Heterotrophic Nitrite Loop
CROSS_FEEDINGHYPOTHESIZED - expressed heterotrophic nitrate-reductase genes could support nitrate-to-nitrite recycling for anammox. The study also identifies other nitrogen-reduction routes; a realized nitrite loop and its contribution were not directly measured.
Participating Taxa: anammox-granule heterotrophic flanking bacteria, Brocadia-affiliated anammox bacterium AMX1
Metabolites: nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech), nitrite (CHEBI:16301 · MediaIngredientMech · CMMMech)
Evidence
-
doi:10.1038/ncomms15416 - PARTIAL (COMPUTATIONAL)"All heterotrophs expressed respiratory nitrate reductase genes"
EPS Peptide Scavenging by Chlorobi
CROSS_FEEDINGHYPOTHESIZED - highly expressed peptidases and peptide/amino-acid transport genes support Chlorobi-affiliated protein scavenging. Extracellular localization and anammox-derived EPS as the substrate are inferred; transfer to other community members was not directly demonstrated.
Participating Taxa: Brocadia-affiliated anammox bacterium AMX1, Chlorobi-affiliated heterotrophic bacteria
Biological Processes:
- proteolysis (GO:0006508 · PathwayMech)
Evidence
-
doi:10.1038/ncomms15416 - PARTIAL (COMPUTATIONAL)"catabolizing extracellular peptides"
-
doi:10.1038/ncomms15416 - PARTIAL (COMPUTATIONAL)"EPS produced by anammox bacteria"
Detritus and Small-Donor Scavenging
CROSS_FEEDINGHYPOTHESIZED - heterotrophic genomes expressed functions compatible with detritus, peptide and small-donor metabolism. The direction of acetate metabolism remains unresolved, and hydrogen/formate use does not establish secretion by AMX1 or exclusive anammox-derived carbon supply.
Participating Taxa: Brocadia-affiliated anammox bacterium AMX1, anammox-granule heterotrophic flanking bacteria
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), formate (CHEBI:15740 · MediaIngredientMech · CMMMech)
Evidence
-
doi:10.1038/ncomms15416 - PARTIAL (COMPUTATIONAL)"scavenging of detritus and peptides"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Anammox granule metagenome and metatranscriptome article
Open-access article reporting genome-centric metagenomics, metatranscriptomics, and metabolic network reconstruction for a laboratory anammox granule community. |
METATRANSCRIPTOMICS | OTHER | Nature-Communications-15416 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which proposed nitrogen and carbon exchanges occur between these granule members?
doi:10.1038/ncomms15416 reconstructs expressed metabolic potential. Acetate pathway direction is explicitly unresolved; cited tracer support for EPS origin comes from other work. The reactor received wastewater filtrate with residual organic carbon. Same-system flux tracing and partner perturbations are required to identify the exchanged substrates and their contributors.
Attaches to: ecological_interactions#Anammox Ammonium-Nitrite Conversion, ecological_interactions#Heterotrophic Nitrite Loop, ecological_interactions#EPS Peptide Scavenging by Chlorobi, ecological_interactions#Detritus and Small-Donor Scavenging
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| anaerobic granule interior | Oxygen diffusion limited by dense aggregate structure | N/A |
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| extracellular polymeric substances | Protein- and polysaccharide-rich EPS matrix | N/A |
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| wastewater nitrogen removal context | High-strength ammonium wastewater treatment model | N/A |
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Growth Media
Cross-Mech Suite Links
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