A defined two-member halophilic synthetic consortium, PES, assembled from Pelagerythrobacter sp. N7 and Salinicola sp. A11, which were isolated from a PAH-degrading consortium enriched from saline PAH-polluted soil in Shanxi Province, China. Washed suspensions of the two isolates were mixed 1:1 and assayed in 5% sea-salt defined medium with 50 mg/L pyrene as the sole carbon source. N7 alone initiated pyrene oxidation but incompletely removed pyrene and accumulated 4,5-dicarboxyphenanthrene, whereas A11 alone had no detectable direct pyrene-degrading capability. In the PES consortium, A11 supplied a proposed hphtC-5-encoded aromatic-acid decarboxylase/downstream C12O arm and extracellular emulsan-like bioemulsifier activity, together enabling complete removal of 50 mg/L pyrene within 10 days at 5% salinity.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Pelagerythrobacter sp. N7 — ontology label: Pelagerythrobacter | NCBITaxon:2800685 · TaxonMech · TraitMech |
PRIMARY_DEGRADER
SYNTROPHIC_PARTNER
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DOMINANT |
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| Salinicola sp. A11 — ontology label: Salinicola | NCBITaxon:404432 · TaxonMech · TraitMech |
CROSS_FEEDER
SYNTROPHIC_PARTNER
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DOMINANT |
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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.
Proposed N7-A11 4,5-dicarboxyphenanthrene handoff
SYNTROPHYPARTIAL - N7 monoculture accumulated 4,5-dicarboxyphenanthrene, while PES contained additional downstream metabolites. The authors infer an N7-to-A11 intermediate handoff and propose hphtC-5 as a candidate A11 decarboxylase from genome annotation, structural modeling and transcripts. These observations do not directly trace intercellular flux or establish enzyme necessity or sufficiency. The published Figure 8 correction confirms the proposed direction from 4,5-dicarboxyphenanthrene to 4-carboxyphenanthrene, not its reverse.
Source Taxon: Pelagerythrobacter sp. N7
Target Taxon: Salinicola sp. A11
Metabolites: pyrene (CHEBI:39106 · MediaIngredientMech · CMMMech)
HYPOTHESIZED - A11-mediated transformation of the intermediate accumulated by N7 could relieve the degradation bottleneck and enable the observed PES pyrene removal. Metabolite profiles, annotation and expression support the proposed pathway but do not isolate hphtC-5-dependent intercellular transfer as the cause of the removal advantage.
Evidence
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PMID:42666409 - SUPPORT (IN_VITRO)"Owing to the inability to further transfer 4,5-dicarboxyphenanthrene, the metabolic pathway was disrupted, leading to the significant accumulation of 4,5-dicarboxyphenanthrene during pyrene degradation by the pure culture of strain N7."
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PMID:42666409 - PARTIAL (COMPUTATIONAL)"enzyme encoded by hphtC-5 was proposed to be the candidate decarboxylase for the decarboxylation process of 4,5-dicarboxyphenanthrene."
A11-Associated Extracellular Emulsifying Activity
A11 and PES cell-free supernatants formed persistent soybean-oil emulsions, unlike N7 supernatant, washed cells or fresh medium; the reported 24-hour emulsification index was 68%. A11 was grown with yeast extract, whereas N7 and PES were grown with pyrene, so this is not a substrate-matched production comparison. FTIR of crude material and genome annotation support an emulsan-like interpretation. HYPOTHESIZED - Its contribution to pyrene bioavailability and N7 degradation is proposed, not isolated by the soybean-oil assay or proof of reciprocal fitness benefit.
Source Taxon: Salinicola sp. A11
Target Taxon: Pelagerythrobacter sp. N7
Metabolites: pyrene (CHEBI:39106 · MediaIngredientMech · CMMMech)
HYPOTHESIZED - Extracellular emulsifying material attributed to A11 could increase pyrene availability and thereby improve PES removal. The measured emulsion phenotype and genomic capacity do not isolate pyrene mass transfer, the export system or the fraction of removal caused by this mechanism.
Evidence
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PMID:42666409 - SUPPORT (IN_VITRO)"Distinct and persistent emulsion layers were observed only in the cell-free supernatants of strain A11 and consortium PES"
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PMID:42666409 - PARTIAL (COMPUTATIONAL)"In the genome of strain A11, wza, wzb, and wzc related genes were identified"
Complete 5%-salinity pyrene removal by PES
SYNTROPHYPES approached complete removal of 50 mg/L pyrene in 200 mL 5%-salinity SSDM within 10 days. N7 removal plateaued at 49.95% after 14 days, and A11 lacked direct PAH-degrading capability. These controlled culture observations support the consortium removal advantage. Residual-substrate HPLC and intermediate detection do not by themselves establish complete carbon mineralization, a closed carbon balance or reciprocal member-specific fitness benefits.
Metabolites: pyrene (CHEBI:39106 · MediaIngredientMech · CMMMech)
Evidence
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PMID:42666409 - SUPPORT (IN_VITRO)"Within a 10-day cultivation period, the removal rate of 50 mg/L pyrene by the consortium PES approached 100%"
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PMID:42666409 - SUPPORT (IN_VITRO)"Strain A11 was detected to be unable to degrade PAHs"
Associated Datasets
| Dataset | Type | Repository | Accession |
|---|---|---|---|
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Salinicola sp. A11 whole-genome shotgun sequencing reads
NCBI SRA read accession for the A11 draft-genome sequencing reported in the primary PES article. |
GENOMICS | NCBI_SRA | SRR38848454 |
Knowledge gaps & discussions (2)
KNOWLEDGE_GAP OPEN Is the A11 hphtC-5 candidate sufficient and necessary for 4,5-dicarboxyphenanthrene decarboxylation inside PES?
The source detected downstream pyrene metabolites in PES, annotated hphtC-5 in the A11 genome, modeled a compatible active site, and measured hphtC-5 expression by RT-PCR. It did not purify HphtC-5 or perturb hphtC-5 genetically, so the specific enzyme assignment remains a candidate step.
Attaches to: ecological_interactions#Proposed N7-A11 4,5-dicarboxyphenanthrene handoff
KNOWLEDGE_GAP OPEN Which candidate enzyme and emulsifier activities cause the measured PES removal advantage?
Preserve positive pyrene removal, intermediate profiles and extracellular emulsification. hphtC-5 remains a candidate, as in the existing gap. Soybean-oil emulsification is not a direct pyrene-solubility or depletion/add-back test; A11 and the other cultures had different growth substrates. The correction DOI10.3389/fmicb.2026.1971230 changes structures in Figure8, not the need for causal validation. No new nodes/arrows are warranted by the inspected main text.
Attaches to: ecological_interactions#Proposed N7-A11 4,5-dicarboxyphenanthrene handoff, ecological_interactions#A11-Associated Extracellular Emulsifying Activity, ecological_interactions#Complete 5%-salinity pyrene removal by PES
2 evidence item(s)
enzyme encoded by hphtC-5 was proposed to be the candidate decarboxylase for the decarboxylation process of 4,5-dicarboxyphenanthrene.
Candidate enzyme assignment based on annotation/modeling and expression, not direct enzymatic validation.
Distinct and persistent emulsion layers were observed only in the cell-free supernatants of strain A11 and consortium PES
Supports A11 and PES, but not N7 alone, as sources of extracellular emulsifying activity.
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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Primary publication - PES halophilic pyrene-degradation SynCom
Frontiers in Microbiology 2026 primary article describing the Pelagerythrobacter sp. N7 and Salinicola sp. A11 halophilic PES SynCom. |
OTHER | PMID:42666409 |
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Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Sodium-chloride-dominated salinity | 1%, 3%, 5%, 8%, and 10% | N/A |
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| Initial pH | 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0 | N/A |
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Growth Media
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