Baby Gut Bacteria Strain Matches Top Probiotic Against Colitis in Mice

If you have ulcerative colitis or love someone who does, you already know the drill: flares that hijack weeks at a time, medications that work until they don't, and a nagging sense that the real trigger lives somewhere in the gut itself. A new mouse study adds a specific, testable piece to that puzzle: a bacterial strain pulled from a healthy breastfed infant's gut calmed colitis-like inflammation about as well as one of the most studied probiotics on the market, and it did so by leaning on a different part of the immune system.

Key takeaways

• A probiotic strain called Lactiplantibacillus plantarum BF_15, isolated from a breastfed infant, reduced colitis severity in mice about as effectively as LGG (Lactobacillus rhamnosus GG), a widely used reference probiotic.
• BF_15 lowered a clinical disease score from 3.00 to 1.16 (out of 4), restored gut bacteria balance, and calmed inflammatory markers in blood, matching LGG's effects on most measures.
• On a molecular level, BF_15 altered far more proteins tied to immune signaling than LGG did, hinting at a broader or different mechanism of action.
• This is a mouse study only. It has not been tested in humans, so no clinical claims can be made about treating ulcerative colitis in people yet.

Infant-Derived Strain BF_15 Eases Colitis Symptoms in Mice

Researchers isolated Lactiplantibacillus plantarum BF_15 (a bacterial species related to common probiotic lactobacilli, but reclassified into the newer Lactiplantibacillus genus in 2020) from the feces of a healthy, exclusively breastfed infant, then tested it in mice with chemically induced colitis, according to a study published in Food Science & Nutrition. Mice given daily BF_15 for three weeks before colitis induction saw their disease activity index (DAI, a combined score of weight loss, stool consistency, and blood in stool) drop from 3.00 to 1.16 out of a possible 4, essentially the same improvement seen with LGG (Lactobacillus rhamnosus GG), which fell to 0.93. LGG is one of the most extensively studied probiotic strains in the world, credited in prior research with boosting gut microbial diversity and shaping immune cell populations in the intestine, according to research summarized by the National Institutes of Health. Colon shortening, a physical marker of inflammation and tissue damage, was also similarly reversed: colons in untreated colitis mice measured 4.43 centimeters on average versus 6.72 centimeters in healthy controls, and BF_15 restored that length to 5.41 centimeters, nearly identical to LGG's 5.37 centimeters.

Why Ulcerative Colitis Patients Should Pay Attention

Ulcerative colitis is a chronic inflammatory bowel disease (IBD) in which the immune system attacks the lining of the colon, and it currently has no cure, only management. In the United States alone, an estimated 1.2% of adults, or roughly 3 million people, have been diagnosed with ulcerative colitis, according to the Centers for Disease Control and Prevention, and the standard drug options (aminosalicylates, steroids, and immunosuppressants) carry real trade-offs with long-term use, including reduced tolerance and disease recurrence. That treatment gap is exactly why researchers keep hunting for new probiotic candidates: a strain that works through a different biological route than existing options could eventually complement, rather than just duplicate, what's already on pharmacy shelves. For anyone managing IBD, IBS, or other gut-immune conditions, new probiotic mechanisms are worth tracking even at this early stage, because they represent potential future tools, not because any of them are ready to use today.

How the Mouse Trial Was Designed

The study used 40 male mice split into four groups of 10: an untreated control group, a group given only the colitis-inducing chemical dextran sulfate sodium (DSS), a group that received BF_15 before DSS exposure, and a group that received LGG before DSS exposure. DSS is a standard, well-established way to trigger colon inflammation in mice that mimics several features of human ulcerative colitis, and it has been used to screen dozens of candidate probiotics in prior research, including other infant-derived Lactobacillus strains tested in similar designs, per a related study published on PubMed Central. Beyond DAI scores and colon length, the researchers measured blood levels of inflammatory signaling molecules (cytokines), profiled the gut bacterial community using 16S rRNA gene sequencing, and ran a large-scale proteomics analysis, a technique that measures thousands of proteins at once, to compare which molecular pathways BF_15 and LGG each switched on or off inside colon tissue.

What This Means If You're Managing Gut Inflammation

For someone currently managing ulcerative colitis, the direct takeaway is limited but not nothing: this adds one more scientifically credible candidate to the pipeline of infant-derived probiotics under investigation for gut-immune conditions, alongside a small but growing list of similar strains from breastfed infants and fermented foods. Blood tests in the mice showed BF_15 reduced pro-inflammatory cytokines IL-6 and IL-17A while raising anti-inflammatory IL-10 (from 565.92 to 656.84 picograms per milliliter) and secretory immunoglobulin A, or SIgA (a gut-specific antibody that helps maintain the mucosal barrier, from 9.75 to 12.79 micrograms per milliliter). It also partially restored the relative abundance of Bacteroidetes, a major beneficial bacterial group that colitis typically depletes, from 28.02% back toward 30.85% (healthy control mice measured 49.92%). None of this means BF_15 belongs in a supplement regimen; it means the strain has cleared an early, legitimate scientific hurdle that most candidate probiotics never reach. Nothing here should be read as a supplement recommendation, and no one should adjust an IBD treatment plan based on a mouse study.

What's Not Yet Known: Mouse-Only Data, No Human Trial

The single biggest limitation, one the study's own authors state plainly, is that BF_15's effects have only been demonstrated in mice, not people, and human clinical trials have not been conducted. Mouse colitis models are useful for narrowing down promising candidates and mapping biological mechanisms, but they routinely fail to predict how a strain will behave in the far more complex human gut and immune system. It's also a single study without independent replication by another lab. Two of the paper's co-authors are employed by a dairy company (New Hope Tensun Hebei Dairy) and are disclosed as having provided technical support such as data curation and figure visualization; the authors state the company provided no funding or lab resources, and the strain's patent is held solely by the university, not the company, so this reads as a disclosed affiliation rather than a funding conflict. Readers should still note it as a data point.

What Comes Next for BF_15

The proteomics data point to where researchers are likely headed next: BF_15 altered 528 proteins in colon tissue compared with untreated colitis mice, versus 161 for LGG, with especially strong effects on the antigen processing and presentation pathway (APC, the immune system's process for flagging threats to immune cells). That's a mechanistic clue, not a finished explanation, and the paper's authors describe it as filling a research gap rather than closing one. The logical next steps, none of which have timelines announced in this paper, are validating the APC pathway findings with more targeted experiments and, eventually, safety and efficacy testing in humans, a process that typically takes years even for promising candidates.

Common Questions

Is this probiotic available to buy or take? No. BF_15 is a laboratory research strain that has only been tested in mice; it is not commercially available or approved for human use.

Does this mean probiotics can replace ulcerative colitis medication? No. Nothing in this study supports replacing prescribed IBD treatment with a probiotic, and no human trials have tested BF_15 for that purpose.

How is BF_15 different from other probiotics like LGG? Both strains reduced inflammation and tissue damage to a similar degree in this study, but BF_15 affected a broader set of proteins in an immune pathway (antigen processing and presentation) than LGG did, suggesting it may work through a somewhat different mechanism, though this remains a hypothesis based on one animal study.

Where did this probiotic strain come from? Researchers isolated it from the fecal samples of a healthy, exclusively breastfed infant, on the theory that infant-derived strains may be especially well-adapted to the human gut.

References

1. Na Zhang, Hongjie Liu, Dongyao Li, et al. (2026). Lactiplantibacillus plantarum BF_15 Confers Protection Against Ulcerative Colitis by Orchestrating Gut Microbiota‐Barrier‐Immune Triad Homeostasis. Food Science & Nutrition. https://doi.org/10.1002/fsn3.72275
2. Chun-wei Shi, Ming-yang Cheng, Xin Yang, et al. (2020). Probiotic Lactobacillus rhamnosus GG Promotes Mouse Gut Microbiota Diversity and T Cell Differentiation. Frontiers in Microbiology. https://doi.org/10.3389/fmicb.2020.607735
3. IBD Facts and Stats | CDC. cdc.gov. https://www.cdc.gov/inflammatory-bowel-disease/php/facts-stats/index.html
4. Anti-Inflammatory and Gut Microbiota Modulatory Effect of Lactobacillus rhamnosus Strain LDTM 7511 in a DSS-Induced Colitis Murine Model. NIH. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356973/