A simplified synthetic microbial community of three gut genera (Cetobacterium, Paraclostridium, and Pseudomonas) assembled from the intestinal microbiota of crucian carp (Carassius auratus). These genera were enriched in fish that displayed mild symptoms after Aeromonas hydrophila infection, and fecal microbiota transplantation from mild-symptom fish conferred enhanced resistance to the pathogen. The reconstituted SynCom significantly reduced A. hydrophila abundance by activating intestinal immune responses and reinforcing the gut barrier, supporting microbiome-based disease prevention in aquaculture.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Cetobacterium | NCBITaxon:180162 · TaxonMech · TraitMech | N/A | |
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| Paraclostridium | NCBITaxon:1849822 · TaxonMech · TraitMech | N/A | |
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| Pseudomonas | NCBITaxon:286 · TaxonMech · TraitMech | 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.
SynCom-associated intestinal immune responses
After 28 days of SynCom feeding, crucian carp showed increased intestinal SOD, CAT, ACP and lysozyme activities versus controls, alongside immune-associated transcript changes and qPCR validation of selected genes. The intestinal immune network for IgA production is a KEGG pathway annotation, not a direct IgA production assay. These treatment-associated host responses do not establish commensal microbial fitness or selective immune mediation of challenge protection.
Participating Taxa: Cetobacterium, Paraclostridium, Pseudomonas
Biological Processes:
- defense response to bacterium (GO:0042742 · PathwayMech)
PARTIAL - prechallenge immune-associated responses could contribute to the improved survival and reduced pathogen DNA loads after SynCom feeding. The treatment comparison supports protection, but no selective immune blockade or rescue establishes these responses as necessary or sufficient mediators.
Evidence
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PMID:41280275 - PARTIAL (IN_VIVO)"the results revealed significant upregulation of immune-related pathways, particularly the intestinal immune network for IgA production"
SynCom-associated intestinal barrier markers
SynCom feeding increased zo-1, occludin and claudin12 transcript levels, and transcriptomics enriched tight-junction-associated pathways. DAO activity also increased; the paper interprets this injury-associated marker as possible mucosal turnover or repair, not an unambiguous improvement in permeability. These results support a barrier-response hypothesis, not direct barrier-protein abundance, selective functional barrier rescue or reciprocal microbial benefit.
Participating Taxa: Cetobacterium, Paraclostridium, Pseudomonas
Biological Processes:
- defense response to bacterium (GO:0042742 · PathwayMech)
PARTIAL - altered barrier-associated transcripts could contribute to lower intestinal and kidney pathogen DNA loads and improved survival after challenge. The SynCom treatment effect is measured, but marker changes and ambiguous DAO activity do not isolate epithelial barrier function as the necessary mediator.
Evidence
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PMID:41280275 - PARTIAL (IN_VIVO)"activation of tight junction signaling pathways was observed"
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PMID:41280275 - SUPPORT (IN_VIVO)"the expression levels of genes related to the intestinal barrier"
SynCom-mediated suppression of Aeromonas hydrophila
After 28 days of three-strain SynCom feeding, challenged crucian carp had 60% survival versus 32.5% in controls and lower calibrated qPCR Aeromonas DNA loads in intestine and kidney. These are positive host treatment outcomes, not merely relative 16S profiles or viable-pathogen counts. Immune and barrier mediation remains proposed, and reciprocal microbial competition is not established. The separate FMT survival comparison (66.7% versus 36.7%) is not the SynCom result.
Participating Taxa: Cetobacterium, Paraclostridium, Pseudomonas
Biological Processes:
- defense response to bacterium (GO:0042742 · PathwayMech)
Evidence
-
PMID:41280275 - SUPPORT (IN_VIVO)"administration of this community significantly improved host resistance to A. hydrophila (p < 0.05) by activating intestinal immune responses and reinforcing the gut barrier"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Which host responses and microbial functions causally mediate SynCom protection?
Complete main-body Methods and Results support 28-day feeding, enzyme/transcript responses, challenge survival and calibrated qPCR pathogen loads. They do not report selective immune/barrier blockade or rescue, direct barrier permeability or barrier-protein validation. Elevated DAO is ambiguous, and the IgA phrase is a pathway annotation. Main text reports non-antagonistic in vitro co-culture and preliminary single/pair/triple feeding comparisons; supplementary images/data were not inspected. In-host cross-feeding and signaling remain hypotheses. Species/strain metadata and conflicting source units/schedules are tracked separately in #1353; canonical genus participants are preserved here.
Attaches to: ecological_interactions#SynCom-associated intestinal immune responses, ecological_interactions#SynCom-associated intestinal barrier markers, ecological_interactions#SynCom-mediated suppression of Aeromonas hydrophila
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