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Rumen Substrate-Adapted Lignocellulose Enrichment Consortia

Community ID CommunityMech:000389
Ecological State ENGINEERED
Environment anaerobic rumen-fluid enrichment culture — ontology label: laboratory environment
ENVO:01001405 · HabitatMech ↗
Modeled Environment rumen — ontology label: digestive tract environment
ENVO:01001033 · HabitatMech ↗

A laboratory panel of rumen-derived anaerobic enrichment consortia selected for 10 serial 72 h generations on four lignocellulosic substrates: alfalfa, barley straw, carboxymethyl cellulose, or a 1:1 arabinoxylan/acetylated-xylan mixture. The enrichments were derived from pooled rumen fluid from cannulated beef heifers in MC medium and were tracked by gas production, volatile fatty acids, and 16S V1-V2 amplicon sequencing. Substrate-specific late consortia showed divergent bacterial profiles, including Prevotella-dominated barley-straw enrichments, Bacteroides-rich CMC enrichments, and xylan enrichments associated with Caproiciproducens, Megasphaera, Lactobacillus, and caproate accumulation; alfalfa and xylan G10 cultures also retained core community structure after one month of cryopreservation and revival.

Taxonomy

Taxon Ontology ID Functional Roles Abundance
Prevotella_1 SILVA group — ontology label: Prevotella NCBITaxon:838 · TaxonMech · TraitMech DOMINANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "the community became progressively dominated by Prevotella_1"
Prevotella_7 SILVA group — ontology label: Prevotella NCBITaxon:838 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Prevotella_1, Prevotellaceae_YAB2003_group and Prevotell_7 remained dominant genera from G3 to G10."
Prevotellaceae_YAB2003_group — ontology label: Prevotellaceae NCBITaxon:171552 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Prevotella_1, Prevotellaceae_YAB2003_group and Prevotell_7 remained dominant genera from G3 to G10."
Rikenellaceae_RC9_gut_group — ontology label: Rikenellaceae NCBITaxon:171550 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "The inoculum (rumen fluid) exhibited a diverse community dominated by Prevotella_1, with substantial contributions from Rikenellaceae_RC9_gut_group, and lower abundances of Anaeroplasma, Lactobacillus, and Bacteroides."
Anaeroplasma NCBITaxon:2086 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "The dominant genera identified in the communities included Anaeroplasma, Bacteroides, Caproiciproducens, Lactobacillus, Megasphaera, Prevotella_1, Prevotella_7, Prevotellaceae_YAB2003_group, Rikenellaceae_RC9_gut_group, and Selenomonas_1"
Bacteroides NCBITaxon:816 · TaxonMech · TraitMech DOMINANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "CMC enrichments showed strong selective pressure, leading to Bacteroides dominating at G3, G6, and G10."
Lactobacillus NCBITaxon:1578 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Caproiciproducens, Lactobacillus and Megasphaera, increased substantially across generations and became major genera by G6 and G10."
Caproiciproducens NCBITaxon:1738645 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "caproate production (6.3 mM at G10) in xylan enrichments associated with Caproiciproducens and Megasphaera."
Megasphaera NCBITaxon:906 · TaxonMech · TraitMech ABUNDANT
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "caproate production (6.3 mM at G10) in xylan enrichments associated with Caproiciproducens and Megasphaera."
Selenomonas_1 SILVA group — ontology label: Selenomonas NCBITaxon:970 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Prevotella_1 and Selenomonas_1 showed their strongest signals at early generations on xylan."
Fibrobacter NCBITaxon:832 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Core taxa with BS enrichment included Rikenellaceae_RC9_gut_group, Prevotellaceae_1, and Fibrobacter."
Sporanaerobacter NCBITaxon:165812 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Bacteroides, Sporanaerobacter, Streptococcus, and Sphaerochaeta were consistently classified as core genera with CMC from G3 through G10."
Streptococcus NCBITaxon:1301 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Bacteroides, Sporanaerobacter, Streptococcus, and Sphaerochaeta were consistently classified as core genera with CMC from G3 through G10."
Sphaerochaeta NCBITaxon:399320 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Bacteroides, Sporanaerobacter, Streptococcus, and Sphaerochaeta were consistently classified as core genera with CMC from G3 through G10."
Bifidobacterium NCBITaxon:1678 · TaxonMech · TraitMech COMMON
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Megasphaera, Caproiciproducens, Bifidobacterium and Lactobacillus displayed sustained or increasing normalized abundance through G3–G6 and into G10."

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.

Ecological interaction network for Rumen Substrate-Adapted Lignocellulose Enrichment Consortia Bipartite graph where circles represent taxa and non-circular symbols represent interactions. Rare or untyped interactions share the Other symbol; exact curated types remain in the interaction details.
Taxon
Other

Four-substrate rumen consortium specialization

Serial 72 h enrichment on alfalfa, barley straw, CMC, or xylan selected different late bacterial profiles from the same pooled rumen-fluid inoculum, with the CMC and xylan enrichments producing the strongest Bray-Curtis separation from the alfalfa and barley-straw lines. Differences among separately enriched lines demonstrate substrate-dependent selection, not reduced competition through niche separation among coexisting members.

Biological Processes:

Downstream Effects:
→ Xylan chain-elongation-associated phenotype

PARTIAL: repeated xylan selection generated the late consortium with caproate accumulation. Genus abundance and bulk end products are consistent with community mediation, but do not isolate the contribution of the compositional shift from substrate effects or demonstrate the proposed member-to-member flux.

Evidence

  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Xylan- and CMC-enriched consortia exhibited the greatest compositional shifts, forming discrete clusters that were distinct from BS and alfalfa communities."
  • PMID:42197533 - SUPPORT (IN_VITRO)
    "Across generations, total VFA concentrations declined on all substrates, with the sharpest decreases observed for xylan and BS."

CMC Bacteroides core selection

The carboxymethyl-cellulose line reproducibly selected a Bacteroides-dominated core with Sporanaerobacter, Streptococcus, and Sphaerochaeta across G3, G6, and G10. The record treats this as substrate enrichment of a CMC-adapted guild, not as a resolved pairwise lactate-propionate exchange. Recurrent abundance does not itself establish complementary niches or competitive release.

Biological Processes:

Evidence

  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "CMC enrichments showed strong selective pressure, leading to Bacteroides dominating at G3, G6, and G10."
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Bacteroides, Sporanaerobacter, Streptococcus, and Sphaerochaeta were consistently classified as core genera with CMC from G3 through G10."

Xylan chain-elongation-associated phenotype

The xylan line selected a Caproiciproducens-, Lactobacillus-, and Megasphaera-rich late community and developed caproate production by G10, a profile the paper interprets as consistent with reverse beta-oxidation but not yet supported by direct flux measurements. These are culture-level endpoints and genus associations, not demonstrated hydrogen diversion, methane suppression or reduced competition.

Biological Processes:

Evidence

  • PMID:42197533 - SUPPORT (IN_VITRO)
    "In xylan enrichments, caproic acid (C6) increased from negligible levels at G0 to 6.33 mM at G10"
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Caproiciproducens, Lactobacillus and Megasphaera, increased substantially across generations and became major genera by G6 and G10."

Associated Datasets

Dataset Type Repository Accession
Rumen substrate-adapted enrichment 16S amplicon BioProject
NCBI BioProject with data for the rumen-fluid substrate enrichment study. 		AMPLICON_16S NCBI_BIOPROJECT PRJNA1433565

Knowledge gaps & discussions (3)

INTERPRETATION OPEN Do the xylan-enriched genera directly redirect rumen fermentation electrons through reverse beta-oxidation and away from methane?

The VFA and 16S profiles support caproate production associated with Caproiciproducens and Megasphaera, but the paper explicitly notes that hydrogen and methane fluxes were not directly measured.

Attaches to: ecological_interactions#Xylan chain-elongation-associated phenotype

1 proposed experiment(s)
Isotopic flux assay for xylan G10 enrichments
Approach: stable-isotope tracing coupled to VFA and gas quantification
Decision: Demonstrate that carbon and reducing equivalents flow into medium-chain carboxylates under xylan enrichment conditions.
1 evidence item(s)
full_text SUPPORT PMID:42197533

direct measurements of hydrogen or methane flux were not performed in our study.

Identifies the measurement gap that prevents a direct hydrogen-flux mechanism from being asserted.

KNOWLEDGE_GAP OPEN Which rumen fungi, protozoa, or genome-resolved bacteria contribute to these substrate-adapted consortia beyond the bacterial 16S genus-level profile?

The record is intentionally bacterial and genus-level because the experiment used 16S V1-V2 amplicons; genome-resolved or eukaryote-inclusive data would be needed to curate exact strains, MAGs, anaerobic fungi, or protozoa.

Attaches to: taxonomy

1 evidence item(s)
full_text SUPPORT PMID:42197533

shorter incubation period of in vitro batch culture and soluble substrate used (CMC and Xylan) favour bacterial over fungal or protozoal growth and thus contributions of these eukaryotes were not considered.

Supports leaving non-bacterial rumen members unresolved.

KNOWLEDGE_GAP OPEN Does community composition mediate the substrate-specific endpoints?

All three positive observations and the existing direction remain. The complete primary main text supports substrate selection, CMC core composition and xylan caproate accumulation, while explicitly relying on inferred metabolic functions. The study does not isolate necessary member contributions or directly measure interspecies flux. Preserve the earlier hydrogen-flux and amplicon-scope discussions; no new pairwise mechanism or niche-partitioning classification is added.

Attaches to: ecological_interactions#Four-substrate rumen consortium specialization, ecological_interactions#CMC Bacteroides core selection, ecological_interactions#Xylan chain-elongation-associated phenotype

1 evidence item(s)
COMPUTATIONAL PARTIAL PMID:42197533

relies on inferred metabolic functions

The primary limitations section bounds interpretation of metabolic networks.

External Resources

Name Repository Resource ID
Rumen-Derived Consortia Microorganisms article
Primary open-access report for the rumen substrate enrichment consortium panel. 		OTHER doi:10.3390/microorganisms14051149

Environmental Factors

Factor Value Unit
lignocellulosic enrichment substrates alfalfa; barley straw; carboxymethyl cellulose; 1:1 arabinoxylan and acetylated xylan N/A
  • PMID:42197533 - SUPPORT (IN_VITRO)
    "Barley straw (BS), alfalfa, carboxymethyl cellulose (CMC) and xylan (mix of arabinoxylan (50%) and acetylated-xylan (50%) were weighed (0.3 g)"
xylan G10 caproic acid 6.33 mM
  • PMID:42197533 - SUPPORT (IN_VITRO)
    "In xylan enrichments, caproic acid (C6) increased from negligible levels at G0 to 6.33 mM at G10"
xylan total VFA decline 109.8 at G0 to 56.37 at G10 mM
  • PMID:42197533 - SUPPORT (IN_VITRO)
    "xylan: 109.8 mM (G0) to 56.37 mM (G10)"
alfalfa and xylan cryopreservation perturbation one month at -80 C before 72 h revival N/A
  • PMID:42197533 - SUPPORT (IN_VITRO)
    "Cryopreserved consortia retained core community structure and fermentation characteristics upon revival."
  • PMID:42197533 - SUPPORT (COMPUTATIONAL)
    "Cryopreserved samples clustered near their respective enrichments, confirming preservation of major community members despite minor restructuring."

Growth Media

MC rumen enrichment medium

Temperature 39 C
Atmosphere ANAEROBIC

Composition

Component Concentration Unit CHEBI
alfalfa, barley straw, carboxymethyl cellulose, or xylan substrate · MediaIngredientMech 0.3 g per vial N/A

Preparation notes: Initial G0 cultures were inoculated with 30 mL of rumen-fluid/MC mixture in 125 mL vials; each subsequent generation was inoculated with 6 mL from the previous generation into 24 mL fresh MC medium plus the respective 0.3 g substrate under oxygen-free CO2.

Evidence

PMID:42197533

"with the ratio of 1:4. Inoculum (30 mL) was transferred to each vial under a stream of O2-free CO2."

PMID:42197533

"Vials were sealed with rubber stoppers and placed in a rotary shaker (125 rpm) in an incubator at 39 °C for 72 h."

PMID:42197533

"After completion of 72 h of incubation, a 6 mL sub-sample was collected and inoculated"

MC-minus glycerol cryopreservation and revival medium

Temperature 39 C
Atmosphere ANAEROBIC

Composition

Component Concentration Unit CHEBI
glycerol · MediaIngredientMech 15 % v/v final N/A
alfalfa or xylan substrate · MediaIngredientMech 0.3 g per revival vial N/A

Preparation notes: Active G10 alfalfa and xylan cultures were mixed 1:1 with anaerobic fresh MC-minus medium plus glycerol to 15% v/v final glycerol, flash-frozen in liquid nitrogen, stored at -80 C for one month, thawed under CO2, and revived for 72 h into the corresponding 0.3 g substrate in fresh MC medium.

Evidence

PMID:42197533

"flash-frozen in liquid nitrogen and subsequently moved to a −80 °C freezer and stored for one month."

PMID:42197533

"Once thawed, contents of the vials were inoculated into 24 mL of fresh MC medium containing 0.3 g of the respective substrate (either alfalfa or xylan) and incubated at 39 °C for 72 h"

Cross-Mech Suite Links

Explore related entities across the CultureBotAI X-Mech knowledge bases:

HabitatMech: anaerobic rumen-fluid enrichment culture ↗ TaxonMech: Prevotella_1 SILVA group ↗ TraitMech: Prevotella_1 SILVA group ↗ TaxonMech: Prevotella_7 SILVA group ↗ TraitMech: Prevotella_7 SILVA group ↗ TaxonMech: Prevotellaceae_YAB2003_group ↗ TraitMech: Prevotellaceae_YAB2003_group ↗ TaxonMech: Rikenellaceae_RC9_gut_group ↗ TraitMech: Rikenellaceae_RC9_gut_group ↗ TaxonMech: Anaeroplasma ↗ TraitMech: Anaeroplasma ↗ TaxonMech: Bacteroides ↗ TraitMech: Bacteroides ↗ CultureMech Growth Media ↗ PathwayMech Pathways ↗