Nagoya University Researchers Uncover Bacterial Constipation Mechanism

Nagoya University scientists have made a groundbreaking discovery in gut health research, identifying a novel condition termed "bacterial constipation." This new gut disease arises when two common intestinal bacteria collaborate to excessively degrade the protective mucus layer in the colon, leading to dehydrated feces and chronic constipation. Unlike traditional views that attribute constipation primarily to sluggish gut motility, this microbial process explains why many patients do not respond to standard laxatives or prokinetic drugs.

The study, published in the journal Gut Microbes on February 19, 2026, highlights the role of the gut microbiome in digestive disorders, positioning Nagoya University at the forefront of microbiome research in Japan.

The Science of Mucin Degradation in Bacterial Constipation

At the heart of bacterial constipation is the colonic mucin layer, a gel-like mucus produced by goblet cells that coats the intestinal wall and hydrates stool. Colonic mucin (Muc2) features terminal sulfate groups that shield it from degradation. Bacteroides thetaiotaomicron, a prevalent gut commensal, produces sulfatase enzymes activated by an anaerobic sulfatase-maturating enzyme (anSME). These sulfatases remove the sulfate groups, exposing the mucin to further breakdown by Akkermansia muciniphila, which deploys glycosylases to consume the desulfated mucin.

This cooperative action—first desulfation by B. thetaiotaomicron, then degradation by A. muciniphila—reduces mucin thickness, impairs lubrication, and causes fecal dehydration. In healthy guts, this process maintains balance, but overabundance tips it toward pathology.

Understanding this step-by-step mechanism opens doors for targeted interventions in microbiome-related disorders.Explore research positions in gut microbiome studies.

Experimental Evidence from Germ-Free Mouse Models

To prove causality, researchers used germ-free (gnotobiotic) mice, colonized singly or dually. Mice with either bacterium alone showed normal defecation—pellet count, moisture, and mucin levels intact. Co-colonization replicated human symptoms: fewer, harder pellets, reduced fecal moisture (down to 60-70%), thinner mucin layer, and increased intestinal permeability measured by FITC-dextran leakage.

• Fecal RNA-seq revealed upregulated sulfate assimilation in A. muciniphila during co-colonization.
• Genetically knocking out anSME in B. thetaiotaomicron preserved mucin, restored moisture, and prevented constipation.

These rigorous controls confirm the synergistic bacterial role, a hallmark of Nagoya University's precise experimental approach.

Human Relevance: Links to Chronic Idiopathic Constipation and Parkinson's

In human cohorts—Parkinson's disease (PD) patients and chronic idiopathic constipation (CIC) cases—fecal analysis showed elevated A. muciniphila and B. thetaiotaomicron, correlating with lower mucin and moisture. CIC affects 10-16% globally, with Japan reporting 6-28% prevalence depending on criteria (Rome III/IV), higher in females and elderly.

PD patients often suffer severe constipation 20-30 years pre-motor symptoms, previously blamed solely on alpha-synuclein in nerves. This bacterial dysbiosis suggests microbiome alterations as an early driver, urging integrated gut-brain research.

Why Current Constipation Treatments Fall Short

Conventional therapies—osmotic laxatives (polyethylene glycol), stimulants, or motility agents—target propulsion but ignore mucin loss. In bacterial constipation, dry stool resists movement despite stimulated contractions. This explains treatment resistance in subsets of CIC and PD patients.

Japan's aging population amplifies the issue; with constipation impacting up to 28% under Rome criteria, novel microbial therapies are urgent.

Promising Treatments: Sulfatase Inhibitors on the Horizon

The study proposes sulfatase inhibitors to block B. thetaiotaomicron's desulfation, preserving mucin. Mouse data supports this; no approved inhibitors exist yet, but microbial enzyme targeting (phages, small molecules) shows promise. Fecal A. muciniphila could serve as a biomarker for patient stratification.

Lead researcher Tomonari Hamaguchi notes: "We genetically modified B. thetaiotaomicron... the mice did not develop constipation; the mucin stayed protected." This could revolutionize care for millions.

Nagoya University's Excellence in Microbiome Research

Housed in the Center for Neurological Diseases and Cancer, Hamaguchi's team leverages Nagoya U's legacy in germ-free animal tech (pioneered 1954). The university excels in neurogenetics and gut-brain axis studies, with prior work on PD microbiome dysbiosis.

Japan leads Asia in microbiome sequencing; Nagoya's facilities support translational research, fostering collaborations.Higher ed opportunities in Japan

Broader Implications for Gut Health and Disease

Bacterial constipation may extend to other dysbioses; mucin degradation links to IBD, infections. PD-gut ties reinforce Braak hypothesis, where alpha-synuclein spreads from gut. Global constipation burden (12% average) demands microbiome-focused strategies.

Future Directions and Research Opportunities

Next: clinical trials for sulfatase blockers, phage therapy, fecal microbiota transplants targeting these bacteria. Longitudinal human studies needed for causality.

Nagoya U seeks collaborators; rising demand for microbiologists in Japan.Research assistant roles | Postdoc positions

Photo by Michael Schiffer on Unsplash

Why This Matters for Higher Education and Careers

This discovery underscores Japan's innovation in life sciences, attracting funding (AMED, JSPS). Aspiring researchers: pursue microbiology at Nagoya U or similar.Browse higher ed jobs | Rate your professors | Career advice | University jobs | Post a job.

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