A defined seven-strain in vitro human-gut model assembled by supplementing a four-strain minimal core with a probiotic Lactobacillus formulation and culturing the resulting whole community in modified MRS medium with 2% fructooligosaccharides. The probiotic arm contained Lactiplantibacillus plantarum PBS067, Lactobacillus acidophilus PBS066, and Limosilactobacillus reuteri PBS072, while the minimal core contained Bacteroides cellulosilyticus CL02T12C19, Clostridium symbiosum WAL-14673, Flavonifractor plautii 1_3_50AFAA, and Escherichia coli ATCC 25922. Finazzi et al. quantified strain dynamics by RT-qPCR, assayed Lactobacillus FOS-utilization genes, profiled SCFAs and organic acids by GC-MS, and tested culture-derived metabolites on palmitate-induced steatotic HepG2 cells.
Taxonomy
| Taxon | Ontology ID | Functional Roles | Abundance |
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| Lactiplantibacillus plantarum PBS067 — ontology label: Lactiplantibacillus plantarum | NCBITaxon:1590 · TaxonMech · TraitMech | N/A | |
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| Lactobacillus acidophilus PBS066 — ontology label: Lactobacillus acidophilus | NCBITaxon:1579 · TaxonMech · TraitMech | N/A | |
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| Limosilactobacillus reuteri PBS072 — ontology label: Limosilactobacillus reuteri | NCBITaxon:1598 · TaxonMech · TraitMech | N/A | |
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| Bacteroides cellulosilyticus CL02T12C19 — ontology label: Bacteroides cellulosilyticus | NCBITaxon:246787 · TaxonMech · TraitMech | N/A | |
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| Clostridium symbiosum WAL-14673 — ontology label: [Clostridium] symbiosum | NCBITaxon:1512 · TaxonMech · TraitMech | N/A | |
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| Flavonifractor plautii 1_3_50AFAA — ontology label: Flavonifractor plautii | NCBITaxon:292800 · TaxonMech · TraitMech | N/A | |
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| Escherichia coli ATCC 25922 — ontology label: Escherichia coli | NCBITaxon:562 · 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.
FOS-driven whole-community strain modulation
After 48 h in the seven-strain community with 2% FOS, species-specific DNA-qPCR estimated about 10^8 bacterial counts/mL for L. plantarum, L. reuteri and E. coli and about 10^7 for B. cellulosilyticus and F. plautii. Calibration used strain-specific genomic-DNA standards, not CFU viability or direct cell counting. Low L. acidophilus abundance and absent scrB expression are associated observations, not selective gene causality. The 1% glucose reference is not carbon-mass matched to 2% FOS.
Participating Taxa: Lactiplantibacillus plantarum PBS067, Lactobacillus acidophilus PBS066, Limosilactobacillus reuteri PBS072, Bacteroides cellulosilyticus CL02T12C19, Clostridium symbiosum WAL-14673, Flavonifractor plautii 1_3_50AFAA, Escherichia coli ATCC 25922
Evidence
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PMID:42781020 - SUPPORT (IN_VITRO)"in the whole community, FOS promotes the growth of L. plantarum PBS067, L. reuteri PBS072, and E. coli reaching values of bacterial counts around ~108 at 48 h"
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PMID:42781020 - SUPPORT (IN_VITRO)"B. cellulosilyticus and F. plautii showed values of ~107 bacterial counts/mL"
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PMID:42781020 - SUPPORT (IN_VITRO)"calibration curves from serial dilutions of strain-specific genomic DNA"
Community-context Lactobacillus FOS-pathway expression
Homology identified putative FOS-utilization genes in the three probiotic strains. RNA/cDNA-qPCR showed community- and time-associated expression differences, including L. plantarum sacA/sacK1 and L. reuteri fructokinase; whole-community 48-h expression excluded L. acidophilus scrB. Expression normalized to species 16S and glucose reference does not establish necessary enzyme activity, inability to use FOS or partner-resolved cross-feeding. Participants name the assayed probiotic members, not every member of the seven-strain culture.
Participating Taxa: Lactiplantibacillus plantarum PBS067, Lactobacillus acidophilus PBS066, Limosilactobacillus reuteri PBS072
Biological Processes:
- carbohydrate metabolic process (GO:0005975 · PathwayMech)
Evidence
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PMID:42781020 - PARTIAL (IN_VITRO)"the differential expression of LP genes (sacA and sacK1) between the monoculture and the probiotic consortium at 48 h suggests that interspecies interactions modulate the transcriptional regulation of FOS utilization pathways"
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PMID:42781020 - SUPPORT (IN_VITRO)"In the reconstructed microbial community at 48 h, all FOS-related genes identified in the probiotic strains were expressed, with the exception of scrB from LA"
Whole-community organic-acid profile broadening
Qualitative GC-MS of derivatized culture extracts showed a broader carboxylic-acid profile for the reconstructed whole community. Figure 7C labels acetic acid, lactic acid and butanoic acid among other peaks; the propanoic-acid marker appears in minimal-core panel B, not separately in panel C. This does not establish physiological absence of propionate from the whole community. Profiles do not measure absolute production, donor-resolved flux or the host-active compound, and glucose-grown profiles were similar. Canonical acetate/butyrate terms represent the reported acid identities, not measured ionic speciation.
Participating Taxa: Lactiplantibacillus plantarum PBS067, Lactobacillus acidophilus PBS066, Limosilactobacillus reuteri PBS072, Bacteroides cellulosilyticus CL02T12C19, Clostridium symbiosum WAL-14673, Flavonifractor plautii 1_3_50AFAA, Escherichia coli ATCC 25922
Metabolites: acetate (CHEBI:30089 · MediaIngredientMech · CMMMech), lactic acid (CHEBI:28358 · MediaIngredientMech · CMMMech), butyrate (CHEBI:17968 · MediaIngredientMech · CMMMech)
Biological Processes:
- fermentation (GO:0006113 · PathwayMech)
Evidence
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PMID:42781020 - SUPPORT (IN_VITRO)"In the probiotic formulation, the metabolic profile showed typical fermentation products of lactobacilli, including acetic acid"
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PMID:42781020 - SUPPORT (IN_VITRO)"The whole reconstructed microbial community exhibited a broader metabolite profile"
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PMID:42781020 - SUPPORT (IN_VITRO)"were qualitatively analyzed using a gas chromatograph"
Knowledge gaps & discussions (2)
KNOWLEDGE_GAP OPEN Which FOS-derived microbial metabolite or metabolite combination causally reduces HepG2 lipid accumulation and Cd36 expression?
Finazzi et al. measured community-level organic-acid profiles and exposed HepG2 cells to extracted bacterial metabolites, but the study reports that the specific metabolites responsible for the observed host-cell response were not identified.
Attaches to: ecological_interactions#Whole-community organic-acid profile broadening, engineering_design
1 proposed experiment(s)
Approach: metabolite fractionation and targeted add-back
Decision: A fraction or reconstructed metabolite mixture that reproduces both reduced lipid accumulation and lower Cd36 expression would nominate a causal metabolite set for follow-up.
1 evidence item(s)
the specific metabolites responsible for the observed effect on host cells were not identified
States the source-level limitation on causal metabolite assignment.
KNOWLEDGE_GAP OPEN How should the extract pretreatment response be represented without inventing its active mediator?
The existing nodes report DNA-qPCR abundance, relative transcript levels and qualitative chemical profiles, not partner-resolved cross-feeding. Actual Figure 7 does not separately label propionate in whole-community panel C; do not infer its biological absence. The source also reports 0.1 mg/mL extract pretreatment of HepG2 for 24 h, removal, then 0.25 mM palmitate for 24 h, with lipid and Cd36 mRNA responses. This missing graph endpoint remains #1450 pending a separately authorized Edison expansion and source review; do not claim graph completeness. Active compounds and Cd36 mediation are unresolved. Preserve the earlier active-metabolite discussion and #1206 role correction. Non-graph pretreatment and readout wording remain #1449.
Attaches to: ecological_interactions#FOS-driven whole-community strain modulation, ecological_interactions#Community-context Lactobacillus FOS-pathway expression, ecological_interactions#Whole-community organic-acid profile broadening
External Resources
| Name | Repository | Resource ID |
|---|---|---|
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PubMed - FOS Lactobacillus probiotic consortium
PubMed record for Finazzi et al. 2026 on FOS-driven metabolism in a defined Lactobacillus-supplemented reductionist human-gut model. |
OTHER | PMID:42781020 |
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DOI - FOS Lactobacillus probiotic consortium
Version-of-record DOI for the Frontiers in Microbiology primary publication. |
OTHER | doi:10.3389/fmicb.2026.1866842 |
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PMC open-access full text
Open-access PMC full text for the Frontiers in Microbiology primary publication. |
OTHER | PMC13599725 |
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Environmental Factors
| Factor | Value | Unit |
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| fructooligosaccharides DP ~ 10 | 2 | % w/v |
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| anaerobic 48 h FOS batch incubation | 48 | h |
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Growth Media
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