Deep saline hydrothermal waters from the Naica Mine crystal cave system in Chihuahua, Mexico. The assayed water samples were collected from the deepest accessible mineshafts, at approximately 700-760 m, and yielded a low-diversity prokaryotic community that included basal Thaumarchaeota, Thermoplasmatales- affiliated Euryarchaeota, Candidate Division OP3, Firmicutes, and Alpha/Beta-proteobacteria. Archaeal ammonia monooxygenase genes supported nitrification by thermophilic chemolithoautotrophic Thaumarchaeota, while unsuccessful sulfate-reducer marker amplification and low electron-donor availability argued against sulfate reduction as a dominant metabolism.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Thaumarchaeota — ontology label: Nitrososphaerota | NCBITaxon:651137 · TaxonMech · TraitMech |
PRIMARY_PRODUCER
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DOMINANT |
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| Thermoplasmatales environmental lineage — ontology label: Thermoplasmatales | NCBITaxon:2301 · TaxonMech · TraitMech | ABUNDANT | |
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| Candidate Division OP3 — ontology label: Candidatus Omnitrophota | NCBITaxon:67812 · TaxonMech · TraitMech | COMMON | |
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| Firmicutes — ontology label: Bacillota | NCBITaxon:1239 · TaxonMech · TraitMech | COMMON | |
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| Alphaproteobacteria | NCBITaxon:28211 · TaxonMech · TraitMech | RARE | |
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| Betaproteobacteria | NCBITaxon:28216 · TaxonMech · TraitMech | RARE | |
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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.
Inferred Thermophily of Naica Archaeal and OP3 Lineages
PARTIAL - Elevated 16S rRNA GC content suggests thermophily of detected archaeal lineages and some OP3 OTUs in Naica hydrothermal waters. This sequence-based inference is not a measured growth-temperature response or demonstrated ecological selection; it does not apply uniformly to all OP3 lineages.
Participating Taxa: Thaumarchaeota, Thermoplasmatales environmental lineage, Candidate Division OP3
Biological Processes:
- response to heat (GO:0009408 · PathwayMech)
Evidence
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doi:10.3389/fmicb.2013.00037 - PARTIAL (IN_VIVO)"high GC content of 16S rRNA gene sequences belonging to the archaea and to some OP3 OTUs suggests that at least these lineages are thermophilic"
Putative Thermophilic Archaeal Ammonia Oxidation
PARTIAL - Archaeal AamoA genes amplified from Naica water support putative ammonia-oxidizing capacity and the authors chemolithoautotrophic interpretation. Gene detection does not measure ammonia oxidation or carbon-fixation flux, assign activity to every detected archaeal lineage, or quantify ammonia and nitrite concentrations.
Source Taxon: Thaumarchaeota
Metabolites: ammonia (CHEBI:16134 · MediaIngredientMech · CMMMech), nitrite (CHEBI:16301 · MediaIngredientMech · CMMMech)
Biological Processes:
- ammonia oxidation (GO:0019329 · PathwayMech)
- carbon fixation (GO:0015977 · PathwayMech)
Evidence
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doi:10.3389/fmicb.2013.00037 - PARTIAL (IN_VIVO)"genes encoding archaeal ammonium monooxygenase (AamoA) were amplified, suggesting that Naica Thaumarchaeota are involved in nitrification"
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doi:10.3389/fmicb.2013.00037 - PARTIAL (IN_VIVO)"These organisms are likely thermophilic chemolithoautotrophs adapted to thrive in an extremely energy-limited environment"
Putative Electron-Donor Limitation of Sulfate Reduction
PARTIAL - Failed dsrA amplification and reported lack of appreciable hydrogen sulfide led the authors to infer that sulfate reduction, if present, was not dominant in the sulfate-rich aquifer. They proposed low organic matter and hydrogen as an electron-donor constraint. Negative PCR is not pathway absence, and this explanation was not a donor-rescue experiment or demonstration of competition. Co-occurring AamoA detection does not establish a causal link to ammonia oxidation.
Metabolites: organic molecular entity (CHEBI:50860 · MediaIngredientMech · CMMMech), hydrogen (CHEBI:18276 · MediaIngredientMech · CMMMech), sulfate (CHEBI:16189 · MediaIngredientMech · CMMMech)
Biological Processes:
- sulfate reduction (GO:0019420 · PathwayMech)
Evidence
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doi:10.3389/fmicb.2013.00037 - SUPPORT (IN_VIVO)"We failed to amplify dsrA genes encoding the dissimilatory sulfite reductase"
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doi:10.3389/fmicb.2013.00037 - PARTIAL (IN_VIVO)"At any rate, for sulfate reduction to occur, either organic matter or inorganic electron donors, typically H2, must be present to fuel the redox reaction. However, both appear to be extremely low in the aquifer"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which observations distinguish activity and causal mediation from inferred potential?
Distinguish high-GC thermophily inference and AamoA capacity from measured growth and metabolic rates. Low-biomass sampling, primer detection limits and contamination considerations bound negative and positive detections. The source presents sulfate reduction as not dominant if present; hydrogen-sulfide absence includes unpublished observations. Test donor rescue and oxidation rates before adding causal arrows among co-occurring environmental explanations. Canonical taxonomic groundings are retained; non-graph physiological metadata needs separate reconciliation.
Attaches to: ecological_interactions#Inferred Thermophily of Naica Archaeal and OP3 Lineages, ecological_interactions#Putative Thermophilic Archaeal Ammonia Oxidation, ecological_interactions#Putative Electron-Donor Limitation of Sulfate Reduction
Environmental Factors
| Factor | Value | Unit |
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| Temperature | 54-60 | °C |
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| Depth | 700-760 | m |
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| Oligotrophy | Extreme | qualitative |
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