A four-member mixed-genus wheat-rhizosphere synthetic consortium (SynCom 6/C6) composed of Streptomyces sp. B6, Chryseobacterium sp. B7, Pseudomonas sp. B12, and Sphingomonas sp. B17. Yin et al. reported that C6 inhibited Rhizoctonia solani AG8 radial growth in dual culture and produced auxin in vitro as a whole consortium.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
|---|---|---|---|
| Streptomyces sp. B6 — ontology label: Streptomyces | NCBITaxon:1883 · TaxonMech · TraitMech |
PATHOGEN_ANTAGONIST
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DOMINANT |
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| Chryseobacterium sp. B7 — ontology label: Chryseobacterium | NCBITaxon:59732 · TaxonMech · TraitMech |
PATHOGEN_ANTAGONIST
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DOMINANT |
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| Pseudomonas sp. B12 — ontology label: Pseudomonas | NCBITaxon:286 · TaxonMech · TraitMech |
PATHOGEN_ANTAGONIST
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DOMINANT |
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| Sphingomonas sp. B17 — ontology label: Sphingomonas | NCBITaxon:13687 · TaxonMech · TraitMech |
PATHOGEN_ANTAGONIST
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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.
C6 Dual-Culture AG8 Radial Inhibition
The assembled C6 inhibited Rhizoctonia solani AG8 radial growth in dual culture, with reported inhibition of 34.48% (SD 5.91) in Table 2. This is a positive fungal-growth outcome, not evidence that both bacterial and fungal fitness declined. Plate inhibition does not establish the mediator or guarantee host protection.
Participating Taxa: Streptomyces sp. B6, Chryseobacterium sp. B7, Pseudomonas sp. B12, Sphingomonas sp. B17
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
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PMID:36118206 - SUPPORT (IN_VITRO)"In vitro dual-culture assay showed eight SynComs, including C1-C4, C6-C8, and C10, inhibited the growth of R. solani AG8 to varying degrees"
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PMID:36118206 - SUPPORT (IN_VITRO)"SynCom 6(C6)34.48 ± 5.91"
C6 Salkowski auxin-assay output
C6 culture supernatant gave an IAA-calibrated Salkowski estimate of 11.76 ug/mL (SD 2.83) in Table 3. This is a whole-mixture colorimetric output, not structural identification of every reactive compound, member-resolved synthesis, delivery to plant roots or mutualism. No selective hormone perturbation links it to the separate Arabidopsis root-length result.
Metabolites: indole-3-acetic acid (CHEBI:16411 · MediaIngredientMech · CMMMech)
Evidence
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PMID:36118206 - SUPPORT (IN_VITRO)"including 10 single strains and all 10 SynComs, produced auxin at various concentrations "
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PMID:36118206 - SUPPORT (IN_VITRO)"SynCom 6(C6)11.76 ± 2.83"
C6-associated Arabidopsis primary-root shortening
C6 was among the nine mixtures that significantly shortened primary roots of plate-grown Arabidopsis after cocultivation. Shorter primary roots are the measured endpoint, not demonstrated growth promotion or reciprocal benefit. The across-treatment association with a separate auxin assay does not establish IAA as the necessary mediator. This Arabidopsis phenotype is not a wheat disease-protection result; C6 was not among the mixtures with significant greenhouse root-rot reduction or fresh-root-weight improvement.
Metabolites: indole-3-acetic acid (CHEBI:16411 · MediaIngredientMech · CMMMech)
Biological Processes:
- growth (GO:0040007 · PathwayMech)
Evidence
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PMID:36118206 - SUPPORT (IN_VIVO)"Similar reductions in the primary root length of Arabidopsis seedlings were observed in all SynComs except C5 "
C6 cell-free contrast with inhibitory member cultures
Cell-free cultures of each C6 member inhibited AG8 when the strains were tested separately, but the assembled C6 was among all ten mixtures whose supernatants showed no reported antifungal activity. Keep both observations: individual secretion-associated inhibition cannot be assigned to the mixed culture. This contrast does not identify an inhibitor, prove degradation of a particular fungal wall component, or show why the mixture lost the measured phenotype.
Participating Taxa: Streptomyces sp. B6, Chryseobacterium sp. B7, Pseudomonas sp. B12, Sphingomonas sp. B17
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:36118206 - SUPPORT (IN_VITRO)"three Pseudomonas sp. strains (B5, B11, and B12), Streptomyces sp. B6, Chryseobacterium sp. B7, and Sphingomonas sp. B17 became irregular shaped and creamy colored "
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PMID:36118206 - SUPPORT (IN_VITRO)"The growth of AG8 treated with these bacterial strains was significantly inhibited "
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PMID:36118206 - SUPPORT (IN_VITRO)"the cell-free supernatants from the rest of the eight bacteria and 10 SynComs did not show any antifungal activities"
C6 volatile contrast with inhibitory member cultures
Each of the four C6 member strains inhibited AG8 in the physically separated volatile assay, but C6 was not one of the four significantly inhibitory mixtures, identified as C2-C4 and C7. Retain the individual positives and mixture contrast without assigning a positive volatile mechanism to C6, identifying particular emitted compounds, or claiming that volatile effects are absent under every possible condition.
Participating Taxa: Streptomyces sp. B6, Chryseobacterium sp. B7, Pseudomonas sp. B12, Sphingomonas sp. B17
Biological Processes:
- biological process involved in interspecies interaction between organisms (GO:0044419 · PathwayMech)
Evidence
-
PMID:36118206 - SUPPORT (IN_VITRO)"the volatiles emitted by nine single strains and four SynComs significantly inhibited the growth of AG8 "
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PMID:36118206 - SUPPORT (IN_VITRO)"They included four Pseudomonas spp. B5, B11, B12, and P25, Streptomyces sp. B6, Chryseobacterium sp. B7, Sphingomonas sp. B17 "
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PMID:36118206 - SUPPORT (IN_VITRO)"Rhodococcus erythropolis B43, and SynComs C2-4, C7"
Knowledge gaps & discussions (1)
KNOWLEDGE_GAP OPEN Why do C6 individual-member phenotypes differ from the assembled mixture and host assays?
All four members showed individual secretion-associated and volatile inhibition, but the corresponding positive mixture results were absent under the tested conditions. C6 retained direct plate inhibition and a measured Salkowski signal; it shortened Arabidopsis primary roots but was not among the significant wheat-protection mixtures. These contrasts need mechanistic resolution, not erased nulls or invented assay-to-assay causal arrows. The paper labels a negative correlation as r-squared; this notation is not copied as a valid variance-explained statistic or silently repaired.
Attaches to: ecological_interactions#C6 Dual-Culture AG8 Radial Inhibition, ecological_interactions#C6 Salkowski auxin-assay output, ecological_interactions#C6-associated Arabidopsis primary-root shortening, ecological_interactions#C6 cell-free contrast with inhibitory member cultures, ecological_interactions#C6 volatile contrast with inhibitory member cultures
2 evidence item(s)
SynComs (C1, C3, C4, C7, C8, C9, and C10) significantly reduced wheat root rot score
the cell-free supernatants from the rest of the eight bacteria and 10 SynComs did not show any antifungal activities
Environmental Factors
| Factor | Value | Unit |
|---|---|---|
| Host plant | Triticum aestivum | N/A |
| Target pathogen | Rhizoctonia solani AG8 | N/A |
| Application | biological control | N/A |
Growth Media
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