Overview

Gut Microbiota Medium (GMM) is the mucin-supplemented broth described by Goodman et al. (2011) Proceedings of the National Academy of Sciences 108:6252, specifically formulated to recover the maximum-diversity culturable fraction of the human gut microbiota — particularly the mucin-degrading members of the gut community that conventional media (BHI, YCFA, mGAM) cultivate poorly. The flagship organism is Akkermansia muciniphila ATCC BAA-835 (= DSM 22959), the verrucomicrobial mucin-degrader implicated in metabolic-health phenotypes (Plovier et al. 2017 Nat Med).

The defining ingredient is porcine gastric mucin (Sigma Type II or Type III, 4 g/L) — a complex glycoprotein that no other commercial culture medium currently supplies. The mucin provides both a fermentable substrate for mucin-degrading organisms (A. muciniphila, Bacteroides thetaiotaomicron mucin-utilisation locus, Ruminococcus torques, R. gnavus reclassified Mediterraneibacter gnavus) and host-glycan signal that primes expression of polysaccharide-utilisation loci. The medium also includes SCFA (acetate 33 mM, propionate 9 mM, isobutyrate / isovalerate / valerate 1 mM each — added post-autoclave inside the AAE), which support cross-feeding of SCFA-utilising Firmicutes. Because no commercially-validated ready-to-rehydrate GMM exists, this product addresses a clear market gap and complements the GMExpression YCFA platform for full-coverage human gut culturomics.

We also have

YCFA Modified Medium · YCFA Full Recipe · YCFA Base · Modified Chopped Meat Broth (ATCC 1490) · Chopped Meat with Carbohydrates · Beef Granules

Package Contents

Each GMExpression GMM kit contains:

  • Mixture A — pre-weighed GMM base (BHI base 18 g/L + yeast extract 5 g/L + Trypticase 5 g/L + glucose 2 g/L + cellobiose 1 g/L + maltose 1 g/L + soluble starch 1 g/L + K2HPO4 + KH2PO4 + NaCl + MgSO4 + CaCl2 + resazurin) for 5 L final volume.
  • Mixture B — porcine gastric mucin (Sigma Type II / III) 20 g + L-cysteine·HCl 2.5 g, pre-blended, N2-flushed PP bag.
  • Stock H — Hemin stock, 25 mg in 5 mL of 0.05 M NaOH.
  • Stock K — Vitamin K1 stock, 50 mg in 5 mL of 95 % ethanol, amber.
  • Stock S — SCFA mixture — concentrated stock of acetate, propionate, iso-butyrate, iso-valerate, valerate in oxygen-free water, glass ampoule, N2-flushed. For post-autoclave addition inside the AAE.
  • 5 × airtight PP storage bags + 5 × heat-resistant rubber bands.
  • Instruction manual (A5 booklet, v1.0) with explicit Goodman-2011 protocol annex.

Customisation options on request: agar variant at 15 g/L for plates; HMO-supplemented variant for infant-gut culturomics; defined-medium variant with bovine submaxillary mucin (Sigma M3895) for vegan / non-porcine pharma applications; supply as PRAS Hungate tubes pre-poured ready for direct inoculation.

Composition — per 1 L equivalent unless stated otherwise

GMM Broth (Goodman 2011 PNAS reference; per 1 L)

ComponentConcentrationFunction
Brain Heart Infusion base (dehydrated)18.0 gRich peptone, glucose, infusion solids base
Yeast extract5.0 gB-vitamins, NAD precursors
Trypticase (pancreatic digest of casein)5.0 gSupplementary peptide source
D-Glucose2.0 gPrimary carbohydrate
Cellobiose1.0 gDisaccharide; supports Ruminococcus, Bacteroides
Maltose1.0 gDisaccharide; supports glucose-derived utilisation
Soluble starch1.0 gPolysaccharide; supports starch-utilising organisms
Porcine gastric mucin (Sigma Type II / III)4.0 gCritical differentiator — supports Akkermansia muciniphila and mucin-degrading commensals; primes polysaccharide-utilisation locus expression
L-Cysteine·HCl·H2O0.5 gReductant; Eh < −150 mV
Hemin (CAS 16009-13-5)5.0 mgRequired by Bacteroides
Vitamin K1 (CAS 84-80-0)1.0 mgMenaquinone precursor
K2HPO4 / KH2PO42.0 g / 1.0 gPhosphate buffer
NaCl, MgSO4, CaCl22.0 g / 0.2 g / 0.05 gMineral mix
Resazurin1.0 mgRedox indicator (pink/red oxidised, colourless reduced)

SCFA mix (Stock S; post-autoclave addition inside AAE; final concentrations in medium)

Short-chain fatty acidFinal concentrationNotes
Sodium acetate33 mM (2.7 g/L equiv)Major SCFA; energy source for acetate-utilising Firmicutes
Sodium propionate9 mM (0.86 g/L equiv)Secondary SCFA; Bacteroides/Akkermansia end-product
Iso-butyric acid1 mM (0.09 g/L equiv)Branched-chain SCFA from leucine/valine catabolism
Iso-valeric acid1 mM (0.10 g/L equiv)Branched-chain SCFA
Valeric acid (n-valeric)1 mM (0.10 g/L equiv)Cross-feeding precursor for valerate-utilising Firmicutes

Pre-autoclaving pH: 7.2 ± 0.2 at 25 °C. Post-SCFA addition target pH: 6.8–7.0 (SCFAs lower pH; verify and adjust if needed).

→Culturomics and Media Navigator

Need help matching this medium to your microorganism — or starting from a target organism and finding the medium that fits? Use the GMExpression Culturomics and Media Navigator: a curated, cross-referenced tool that lets you (i) start from a medium and view the bacterial taxa it is recommended for, or (ii) start from a target organism (genus, species, or DSMZ/ATCC strain ID) and view the panel of GMExpression media that will support it. The Navigator integrates Gut Microbiota Medium with the wider YCFA, Chopped Meat Broth, BHI-S, Wilkins-Chalgren, Modified GAM, Anaerobic Columbia Blood Agar, M2GSC, BBE, KVLB, CCFA, TPY, and Egg Yolk Agar catalogue.

Use and Applications

  • Maximum-diversity culturomics of the human gut microbiota per Goodman et al. (2011) protocol. The benchmark medium for studies aiming to recover the broadest cultivable fraction of human stool / colonic mucosa.
  • Targeted enrichment of Akkermansia muciniphila ATCC BAA-835 / DSM 22959 for live-biotherapeutic-product manufacturing (Plovier et al. 2017 Nat Med 23:107; A2-Akkermansia is a clinical-development asset).
  • Mucin-degradation phenotyping of new isolates and gut commensals — colonies on GMM agar can be tested for mucin-clearing zones (mucinolysis assay).
  • Cross-feeding studies of SCFA-utilising butyrate producers (Faecalibacterium, Roseburia, Anaerobutyricum hallii) growing on acetate and propionate cross-fed from primary fermenters.
  • Polysaccharide-utilisation locus (PUL) induction studies in Bacteroides thetaiotaomicron and related glycan-utilisers, where the porcine gastric mucin serves as the inducer signal.
  • Cultivation-validated isolation of gut commensals from murine stool in gnotobiotic colonisation studies — Goodman et al. 2011 used GMM to construct defined community models for gnotobiotic mouse work.
  • Stool-bank QC for fecal microbiota transplantation (FMT) consortium-validation workflows.

Compatible Microorganisms

Mucin-degraders (the GMM signature group)

  • Akkermansia muciniphila (ATCC BAA-835 = DSM 22959) — verrucomicrobial flagship organism; intestinal-mucin specialist; not recoverable on standard BHI/YCFA
  • Bacteroides thetaiotaomicron (ATCC 29148) — extensive mucin-utilisation locus repertoire
  • Mediterraneibacter gnavus (formerly Ruminococcus gnavus; reclassified Togo et al. 2018 / Lawson et al. 2023)
  • Ruminococcus torques — mucin-degrading commensal
  • Bifidobacterium bifidum — extracellular endo-β-galactosidases acting on mucin glycans

SCFA-utilising butyrate producers (cross-feeding on the SCFA mix)

  • Faecalibacterium prausnitzii (DSM 17677) — acetate utilisation for butyrate production
  • Roseburia intestinalis (DSM 14610)
  • Agathobacter rectalis (formerly Eubacterium rectale; reclassified Rosero et al. 2016)
  • Anaerobutyricum hallii (formerly Eubacterium hallii; reclassified Shetty et al. 2018)
  • Anaerostipes caccae, A. hadrus

General gut commensals

  • Bacteroides fragilis, B. vulgatus, B. uniformis, B. ovatus, B. caccae
  • Parabacteroides spp.
  • Bifidobacterium spp. (TPY preferred for selective Bifidobacterium isolation)
  • Lactobacillus sensu lato (per Zheng et al. 2020 reclassification)
  • Eubacterium limosum
  • Christensenella minuta (DSM 22607)
  • Coprococcus catus, C. eutactus

Preparation

1Weigh Mixture A. Use the pre-weighed Mixture A (~36.5 g per litre). Tare a clean autoclavable Schott bottle of at least 1.5× final volume.
2Suspend and heat-dissolve. Add Mixture A to 900 mL of distilled water. Heat with frequent agitation to 95–100 °C until fully dissolved (10–12 min — the rich BHI-derived base requires extended heating).
3Add Mixture B (mucin + cysteine). Cool the medium to ~80 °C. Open the N2-flushed Mixture B bag inside an AAE (or use an oxygen-purged needle-and-septum technique). Add the contents to the medium with vigorous stirring. Mucin will dissolve / disperse slowly — continue stirring at 80 °C for 5–8 min until uniformly suspended. The medium will appear hazy / opalescent — this is normal.
4Add pre-autoclave supplements. Pipette 1 mL of Stock H (5 mg/mL hemin) and 0.1 mL of Stock K (10 mg/mL Vitamin K1) directly into the warm solution. Swirl to dissolve.
5Adjust pH and final volume. Cool briefly to ~45 °C. Verify pH; target 7.2 ± 0.2 at 25 °C. Adjust with 1 M NaOH or 1 M HCl. Bring final volume to 1000 mL with distilled water.
6Dispense. Broth tubes: 5–10 mL per Hungate or screw-cap tube. Leave space (≥ 1 cm headspace) for post-autoclave SCFA addition.
7Autoclave. 121 °C × 15 min (103 kPa). Slow cooling. Note: mucin partially hydrolyses during autoclaving — this is expected and does not impair function; the bioactive O-linked glycans remain intact.
8Cool and reduce. Transfer to AAE while still warm. Allow 24-h equilibration. Verify reduction by resazurin colour change (pink → colourless).
9Add SCFA mix inside AAE. Once the medium is reduced and ≤ 50 °C, open the Stock S ampoule inside the AAE and add the specified volume per litre (e.g., 5 mL of 200× concentrate, or follow the lot-specific addition card). Gently swirl. Final SCFA concentrations should be acetate 33 mM, propionate 9 mM, branched-chain SCFAs 1 mM each.
10Recheck pH. Verify final pH 6.8–7.0 after SCFA addition. Adjust with sterile 1 M NaOH if < 6.8.

Critical control points

  • Mucin source and grade. Use Sigma Type II (M2378, partially purified) or Type III (M1778, more highly purified). Other mucin sources (bovine submaxillary, ovine intestinal) work but give different growth kinetics for A. muciniphila specifically. Document the mucin source in the QA file.
  • SCFA addition order. SCFAs must be added after autoclaving (they would partially evaporate and degrade at 121 °C). Add inside the AAE after the medium is reduced and cooled to ≤ 50 °C. Final pH check is mandatory.
  • Resazurin reduction verification. Before inoculation, the medium must be visually colourless (pink-red = oxidised, will not support A. muciniphila or other strict anaerobes). 24-h pre-reduction inside the AAE is standard.

Cautions

Mucin haze is normal. Prepared GMM appears hazy or opalescent due to mucin partial-suspension. This is the correct appearance. Clear medium indicates insufficient mucin (verify Mixture B weight) or excessive mucin degradation (over-autoclaving).
Porcine biosecurity. Porcine gastric mucin is a porcine-derived component. EU, Japan, Canada, and other regions may apply zoosanitary checks. Sigma Type II / III mucin is produced from food-grade porcine stomach with TSE-equivalent safeguards; documentation pack on request.
Bovine biosecurity. BHI base in Mixture A contains calf-brain and beef-heart infusion solids (DAFF EX188M-certified, same pipeline as YCFA and BHI-S).
Vegan / pharma alternative. Bovine submaxillary mucin (Sigma M3895) is available as a custom-order alternative for facilities that exclude porcine components. The substitution affects A. muciniphila growth kinetics slightly but is functionally equivalent for most workflows.
SCFA volatility. Acetate, propionate, and the branched-chain SCFAs are volatile. The Stock S ampoule is N2-flushed and sealed; once opened, use within 24 h. Do not aerosolise the SCFA stock — the smell is intense even at low concentrations.
Mucin batch variability. Mucin is a complex biological material with batch-to-batch variability in glycosylation and protein:carbohydrate ratio. Each batch of prepared GMM should be QC-tested with A. muciniphila growth (OD600 ≥ 0.4 at 48 h).

Storage and Expiry · Safety

  • Dehydrated Mixture A: 15–30 °C in original packaging. Shelf life 30 months.
  • Mixture B (mucin + cysteine, N2-flushed): 4 °C in original sealed packaging. Shelf life 12 months sealed; use within 14 days of opening (mucin is hygroscopic and cysteine oxidises).
  • Stock H, Stock K: as for BHI-S — 4 °C, light-protected; 8 weeks (hemin), 6 months (VK1).
  • Stock S (SCFA, glass ampoule, N2-flushed): 4 °C. Sealed shelf life 12 months; use opened ampoule within 24 h.
  • Prepared broth, aerobic 4 °C: 2 weeks routine (mucin is a perishable substrate).
  • Prepared broth, anaerobic (vacuum-sealed + O2 absorber): 8 weeks for strict-anaerobe use.

Safety notes. Porcine and bovine biological components. Mucin in dust form is a respiratory irritant — handle Mixture B inside a laminar-flow hood or fume hood. SCFAs are odorous; perform Stock S addition under controlled ventilation. SDS available on request.

References

  1. Goodman AL, Kallstrom G, Faith JJ, Reyes A, Moore A, Dantas G, Gordon JI. (2011). Extensive personal human gut microbiota culture collections characterized and manipulated in gnotobiotic mice. PNAS 108(15): 6252–6257. doi: 10.1073/pnas.1102938108. [Primary reference for GMM]
  2. Plovier H et al. (2017). A purified membrane protein from Akkermansia muciniphila or the pasteurized bacterium improves metabolism in obese and diabetic mice. Nature Medicine 23(1): 107–113.
  3. Derrien M, Vaughan EE, Plugge CM, de Vos WM. (2004). Akkermansia muciniphila gen. nov., sp. nov., a human intestinal mucin-degrading bacterium. IJSEM 54: 1469–1476.
  4. Browne HP et al. (2016). Culturing of 'unculturable' human microbiota reveals novel taxa and extensive sporulation. Nature 533: 543–546.
  5. Lagier J-C et al. (2016). Culture of previously uncultured members of the human gut microbiota by culturomics. Nature Microbiology 1: 16203.
  6. Rosero JA et al. (2016). Reclassification of Eubacterium rectale in the genus Agathobacter. IJSEM 66: 768–773.
  7. Shetty SA, Zuffa S, Bui TPN, Aalvink S, Smidt H, de Vos WM. (2018). Reclassification of Eubacterium hallii as Anaerobutyricum hallii. IJSEM 68: 3741–3746.
  8. Sigma-Aldrich product specifications: Mucin from porcine stomach Type II (M2378) and Type III (M1778).

Frequently Asked Questions

Q1. Why use GMM instead of YCFA for gut culturomics?
YCFA and GMM are complementary. YCFA is optimised for SCFA-utilising butyrate producers (Faecalibacterium, Roseburia) and gives excellent recovery of the Firmicutes-dominant fraction. GMM is optimised for mucin-utilising organisms (Akkermansia muciniphila, Bacteroides thetaiotaomicron, Mediterraneibacter gnavus) that YCFA does not recover well. For maximum-diversity culturomics from human stool, use both media in parallel — Goodman et al. (2011) demonstrated that GMM + YCFA together captured ~60 % of 16S-detected taxa, ~2× the recovery of either medium alone.
Q2. Is there a commercial ready-to-rehydrate GMM available from BD or Sigma?
No. As of the current literature search, GMM exists only as a published recipe (Goodman 2011 PNAS supplementary methods). The GMExpression product is the first commercially-validated ready-to-rehydrate GMM kit. This addresses a documented gap in the gut-culturomics-research market — labs currently must source ~12 individual ingredients (including hard-to-source porcine mucin and SCFA mix) and prepare from scratch each time.
Q3. Can I omit the mucin to use GMM as a generic anaerobe medium?
GMM without mucin is functionally equivalent to a richer BHI-S (the base + SCFA mix). For a generic gut-anaerobe medium without mucin, use the GMExpression YCFA Modified Medium (GMNB-YCFA02) or BHI-S (GMNB-BHIS01) instead — these are cheaper and equally appropriate. GMM's commercial premium is specifically for mucin-dependent organism recovery.
Q4. Why does the SCFA addition happen after autoclaving?
Two reasons: (i) Acetate, propionate, and the branched-chain SCFAs are volatile (boiling points 118–187 °C) — autoclaving at 121 °C would cause partial loss. (ii) Free SCFAs at the specified concentrations lower the pH below 7 — this is acceptable in the final medium but interferes with the autoclave pH-equilibration. Post-autoclave addition inside the AAE achieves both correct concentration and correct final pH.
Q5. Can I substitute porcine mucin with another mucin source?
Sigma Type II (M2378) or Type III (M1778) porcine gastric mucin is the Goodman 2011 reference. Sigma M3895 bovine submaxillary mucin is the validated alternative for facilities excluding porcine components (custom order). Reagent-grade chemically-defined glycans (e.g., 2'-fucosyllactose) can be added to a defined-glycan variant for specific PUL-induction studies, but the broad-spectrum culturomics performance of GMM depends on the complex glycan composition of natural mucin.
Q6. What is the expected colony morphology of Akkermansia muciniphila on GMM agar?
Small (0.5–1.5 mm) circular, convex, smooth, white-to-cream-coloured colonies after 48–72 h anaerobic incubation at 37 °C. A. muciniphila is a non-haemolytic, non-spore-forming, oval-shaped, Gram-negative-staining (verrucomicrobial outer-membrane lipopolysaccharide-distinct) organism. Confirm identity by mucin-clearing-zone assay (visible halo of clearing around the colony on mucin-supplemented agar).
Q7. How does GMM compare to mGAM for gut-microbiome recovery?
GMM gives substantially better recovery of mucin-utilising organisms (Akkermansia, R. torques, M. gnavus) than mGAM. mGAM gives slightly better recovery of Bacteroides and Prevotella due to its richer digest-serum + liver-extract base. For the broadest culturomics coverage, use GMM + YCFA + mGAM in parallel. For routine clinical or pharma anaerobic culture, mGAM or YCFA Modified are more cost-effective.
Q8. Is the medium suitable for fermenter / bioreactor scale-up?
Yes, with adjustments. The mucin component foams during gas sparging (N2/CO2 agitation in a bioreactor); add 0.05 mL/L food-grade silicone antifoam. The SCFA addition must be made in-situ inside the closed bioreactor under N2 headspace. Bioreactor protocols available from GMExpression technical support. Note that pure-culture fermentation of A. muciniphila as a live-biotherapeutic-product manufacturing platform has additional regulatory considerations (GMP, microbial-cell-bank standards) beyond the medium itself.