A natural marine water-column microbial community from Saanich Inlet, a seasonally anoxic fjord on Vancouver Island, Canada that serves as a model oxygen minimum zone. Integrated geochemistry, rate measurements, metagenomics, metatranscriptomics, metaproteomics, and qPCR link community structure to coupled carbon, nitrogen, and sulfur cycling across a redox gradient, including SUP05-driven incomplete sulfide-dependent denitrification, nitrite leakage supporting anammox, and a complementary nitrous oxide reduction niche.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| SUP05 Gammaproteobacteria — ontology label: Gammaproteobacteria | NCBITaxon:1236 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
CROSS_FEEDER
|
DOMINANT |
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| anammox bacteria — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
|
N/A |
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| unidentified nitrous oxide reducers — ontology label: Bacteria | NCBITaxon:2 · TaxonMech · TraitMech |
CROSS_FEEDER
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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.
SUP05 Nitrite Leakage Supports Anammox
CROSS_FEEDINGHYPOTHESIZED: a calibrated gene-centric model predicts that nitrite released during SUP05-associated incomplete sulfide-driven denitrification supplies anammox at the sulfide-nitrate transition zone. Geochemical, multiomic and process-rate comparisons support the modeled coupling, but the leakage fraction is a fitted parameter, not an independently measured donor-to-recipient transfer rate.
Source Taxon: SUP05 Gammaproteobacteria
Target Taxon: anammox bacteria
Metabolites: nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech), nitrite (CHEBI:16301 · MediaIngredientMech · CMMMech), hydrogen sulfide (CHEBI:16136 · MediaIngredientMech · CMMMech), ammonium (CHEBI:28938 · MediaIngredientMech · CMMMech)
Biological Processes:
- denitrification (GO:0019333 · PathwayMech)
Evidence
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PMID:27655888 - SUPPORT (COMPUTATIONAL)"nitrite leakage during incomplete sulfide-driven denitrification by SUP05 Gammaproteobacteria is predicted to support inorganic carbon fixation and intense nitrogen loss via anaerobic ammonium oxidation."
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PMID:27655888 - SUPPORT (COMPUTATIONAL)"incomplete sulfide-driven denitrification can be an important precursor for anammox"
Complementary Nitrous Oxide Reduction Niche
HYPOTHESIZED: the absence of nosZ in available SUP05 genomic reconstructions, co-occurring gene profiles and the calibrated model support complementary nitrous oxide reduction by unidentified community members. This metabolic division is not evidence of spatial separation or demonstrated reduction of competition; the functions co-occur around the transition zone.
Source Taxon: SUP05 Gammaproteobacteria
Target Taxon: unidentified nitrous oxide reducers
Metabolites: nitrous oxide (CHEBI:17045 · MediaIngredientMech · CMMMech), hydrogen sulfide (CHEBI:16136 · MediaIngredientMech · CMMMech)
Biological Processes:
- denitrification (GO:0019333 · PathwayMech)
Evidence
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PMID:27655888 - SUPPORT (COMPUTATIONAL)"The absence of nosZ from SUP05 suggests that incomplete nitrate reduction by SUP05 and reduction of nitrous oxide by unidentified community members constitute separate and complementary metabolic niches"
Redox-Driven Pathway Partitioning
PARTIAL: the calibrated steady-state model predicts depth-dependent aerobic and anaerobic pathway distributions consistent with measured molecular and geochemical profiles. The modeled domain is the stratified 100-200 m water column in early 2010. Environmental pathway sorting is retained without asserting reduced competition or general validity during all seasonal renewal conditions.
Metabolites: dioxygen (CHEBI:15379 · MediaIngredientMech · CMMMech), nitrate (CHEBI:17632 · MediaIngredientMech · CMMMech), hydrogen sulfide (CHEBI:16136 · MediaIngredientMech · CMMMech)
Biological Processes:
- nitrification (GO:0019329 · PathwayMech)
- denitrification (GO:0019333 · PathwayMech)
HYPOTHESIZED: overlapping nitrate and sulfide supplies support modeled SUP05 denitrification whose fitted nitrite leakage supplies anammox at the transition zone. Agreement with observations supports this interpretation but is not an isolated transfer experiment.
HYPOTHESIZED: redox and substrate availability support complementary partial denitrification and nitrous oxide reduction at the same transition zone. This is metabolic complementarity, not demonstrated spatial segregation or competition relief.
Evidence
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PMID:27655888 - SUPPORT (COMPUTATIONAL)"the model predicts a redox-driven partitioning of pathways across the water column."
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
|
Saanich Inlet 2010 multiomic redox-gradient profiles
Supplementary metagenomic, metatranscriptomic, metaproteomic, qPCR, geochemical, and rate data used in the Saanich Inlet gene-centric biogeochemical model. |
OTHER | OTHER | PNAS-1602897113-Datasets-S1-S2 |
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN How directly are the fitted transfers and complementary guild identities established?
The primary model is calibrated to geochemical profiles and compared with multiomic and process-rate observations. Retain this substantial support, but distinguish the fitted nitrite leakage mechanism and unidentified nitrous oxide reducers from experimentally isolated transfers. Complementary pathway distributions do not establish the competition-reduction semantics of NICHE_PARTITIONING. No model extension or additional pathway is introduced.
Attaches to: ecological_interactions#SUP05 Nitrite Leakage Supports Anammox, ecological_interactions#Complementary Nitrous Oxide Reduction Niche, ecological_interactions#Redox-Driven Pathway Partitioning
1 evidence item(s)
nitrite leakage during incomplete sulfide-driven denitrification by SUP05 Gammaproteobacteria is predicted to support inorganic carbon fixation and intense nitrogen loss via anaerobic ammonium oxidation.
Supports cross-feeding of nitrite from SUP05-linked denitrification to anammox.
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Seasonally anoxic fjord oxygen minimum zone | Saanich Inlet, Vancouver Island, Canada | N/A |
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| Sulfide-nitrate transition zone | model domain between 100 and 200 m at station SI03 | N/A |
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