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Updated: May 8, 2026
Agarose-Based Model Ecosystem for Cultivating Methanotrophs in a Methane-Oxygen Counter Gradient
Published on: September 6, 2024
Preliminary studies demonstrating acetoclastic methanogenesis in a rat colonic ring model
Edward A Carter1, Ronald G Barr
1Departments of Pediatrics, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA ; Montreal Children's Hospital Research Institute, McGill University, Montreal, QC, Canada ; Pediatric Gastrointestinal Unit, Massachusetts General Hospital, 114 16th Street (114-3503), Charlestown, MA 02129-4004, USA.
Rat colonic rings produce significant hydrogen and methane gas in vitro, influenced by bacterial growth and pH. This gas production mirrors in vivo conditions and suggests attached microbiota can utilize colonic tissue for sustenance.
Area of Science:
- Gastroenterology
- Microbiology
- Physiology
Background:
- The colon hosts a dense anaerobic microbiota responsible for fermenting undigested substrates.
- Intestinal gas production, including hydrogen (H2) and methane (CH4), is a common physiological process.
- Understanding the factors influencing in vitro gas production is crucial for modeling in vivo colonic conditions.
Purpose of the Study:
- To investigate in vitro gas (H2 and CH4) production by washed rat colonic rings.
- To determine the influence of incubation time, substrate availability, and pH on gas production.
- To correlate gas production with changes in microbiota and metabolite concentrations.
Main Methods:
- Washed rat colonic rings were incubated anaerobically (under N2) at physiological conditions.
- Gas concentrations (H2, CH4) were measured after 1 and 24 hours.
- Lactose was added as an exogenous substrate to assess its effect.
- Bacterial colony counts and acetate/lactate concentrations were quantified.
Main Results:
- Negligible H2 and some CH4 were detected after 1 hour; high concentrations of both gases were found after 24 hours.
- Lactose addition significantly stimulated H2 and CH4 production.
- Optimal H2 production occurred at pH 7.0, while CH4 production peaked between pH 4.0 and 6.0.
- Increased gas production at 24 hours correlated with a 10^4-fold increase in anaerobic bacteria and a 100-fold increase in acetate.
Conclusions:
- Rat colonic ring preparations can model in vivo colonic gas production.
- Gas production is significantly influenced by microbiota density, pH, and metabolite formation.
- Attached colonic microbiota can utilize host tissue for growth in the absence of exogenous substrates.
