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Not medical advice. The Atlas is not a substitute for a clinician who can examine you.

Bacillus subtilis

Spore Strain · HU58 / DE111

Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.

4 human trials, about 40 studies, ~1,500 participants. The written rationale for this grade is still being prepared.

FDA
GRAS
WADA
Not prohibited

Reference only. Not medical advice.

What can go wrong

In healthy people B. subtilis is generally well tolerated, with no serious adverse effects reported up to roughly 10 billion CFU/day in the trials to date. The meaningful caution is for people who are immunocompromised: a documented case report (Oggioni et al., J Clin Microbiol 1998) described recurrent B. subtilis septicemia in a 73-year-old with chronic lymphocytic leukemia after a commercial spore preparation, and later reviews echo that severely immunocompromised patients face rare but real Bacillus bloodstream-infection risk from live-organism products. Because these strains are naturally antibiotic-resistant and produce antimicrobial compounds, the theoretical diversity-disruption question raised for spore probiotics applies here too, and long-term human data are limited. Anyone who is immunocompromised, seriously ill, pregnant, or considering it for a child should consult a qualified healthcare provider before use rather than self-prescribing.

Bacillus subtilis is a spore-forming bacterium found in soil and, as the variety B. subtilis natto, in the traditional Japanese fermented soybean food natto. Because it forms heat- and acid-resistant spores, it survives stomach transit and germinates in the small intestine, which makes it shelf-stable and a common ingredient in spore-based supplements under strain names such as DE111 and HU58. It is one of the most-studied bacteria in biology and a workhorse of industrial fermentation. Human evidence for supplement benefit is early: small, mostly industry-funded trials of DE111 report signals in immune-cell activity and shorter duration of some digestive symptoms, while overall microbiome composition, respiratory infection, and most inflammation markers were unchanged. Its long food-safety record in natto is well established; proven clinical benefit as a capsule is not yet.

A soil and natto bacterium that makes its own antibiotics to crowd out pathogens.

What people take it for

These are the reasons people give for taking it. They are not effects it has been shown to have.

  • Immune modulation (early signal: regulatory T-cell activity after immune challenge, DE111)
  • Shorter duration of some digestive symptoms in early trials (DE111)
  • Pathogen competitive exclusion via antimicrobial-compound production
  • Shelf-stable, acid- and heat-resistant spore delivery
  • Traditional dietary organism via natto (and a rich natto-derived source of vitamin K2 MK-7)
  • Industrial enzyme production and animal-feed probiotic (established, non-supplement uses)

What people get wrong

  • Often saidMaking natural antibiotics means it sterilizes your gut

    ActuallyThe dozens of antimicrobial compounds B. subtilis can produce (surfactin, subtilin, iturin, fengycin and others) are targeted competitive-exclusion agents against rival microbes, not broad sterilants; in the DE111 pediatric trial alpha diversity actually rose. That said, the same competitive mechanism is exactly why long-term effects on beneficial diversity still warrant measurement. (Frontiers in Microbiology 2019 review; Beneficial Microbes DE111 pediatric trial)

  • Often saidIt is a proven immune and digestive remedy

    ActuallyHuman supplement trials are small and mostly industry-funded. DE111 showed a regulatory T-cell signal after LPS stimulation and shorter duration of some GI symptoms, but no change in overall microbiome equilibrium, respiratory-infection rate, or most inflammation markers, and the lead authors called their own results preliminary and underpowered. (Freedman et al., Int J Mol Sci 2021)

  • Often saidBecause natto is a rich vitamin K2 source, B. subtilis supplements deliver that benefit too

    ActuallyThe MK-7 (vitamin K2) content is a property of the natto fermentation of soybeans, not something a spore capsule automatically supplies; MK-7 supplements are made by fermenting substrate, not by taking a probiotic. (Nutrition/ScienceDirect MK-7 literature)

  • Often saidIt is a native gut resident that colonizes you

    ActuallyB. subtilis is chiefly a soil and food organism; ingested spores germinate transiently in the small intestine (within about 3 hours in the ileostomy study) and are largely cleared, rather than establishing permanent residence. (Colom et al., 2021 germination study)

Who profits, and who pushes back

  • Maurizio Oggioni and colleagues

    Pushes backAuthors, J Clin Microbiol 1998 case report

    They documented recurrent septicemia in an immunocompromised patient traced to probiotic strains of Bacillus subtilis, concluding that live-organism products carry real risk for severely immunocompromised people and should be used cautiously in that group.

  • Microbiome-diversity researchers

    Pushes backCompetitive-exclusion caution

    A bacterium that produces antibiotics to outcompete others is effective against pathogens but raises legitimate questions about its effect on beneficial gut diversity that short, sponsor-funded trials have not yet answered.

  • Independent evidence reviewers

    Pushes backReading of the DE111 trial base

    The human trials are small and funded by the ingredient manufacturer, and they are null on overall microbiome composition and respiratory infection, so the honest label is 'preliminary,' the word the study authors themselves used.

  • Spore-probiotic brands

    Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.

    Promotes itDTC

    Feature B. subtilis (often HU58) for immune claims; commercial interest.

  • Natto and fermented-food advocates

    Promotes itMixed

    Point to B. subtilis natto as a traditional dietary source.

Where the research comes from

Share of published research by country of origin.
PlaceShare of published research
USA36%
Europe30%
Asia20%
Other14%

Research published from: Global.

How we got here

Bacillus subtilis reached people first as food, not as a supplement. Its variety B. subtilis natto ferments the Japanese dish natto, whose lineage traces through Chinese fermented soybeans (douchi) and is bound up with early Japanese practice: the name natto is associated with the Heian period and the dish with legends around Minamoto no Yoshiie's northeastern campaigns of 1086 to 1088, traditionally made by wrapping boiled soybeans in rice straw carrying wild Bacillus. Natto is among the richest known food sources of vitamin K2 (menaquinone-7), synthesized by the bacterium during fermentation. Western science arrived later: Ehrenberg described Vibrio subtilis in 1835, and Ferdinand Cohn renamed and placed it in the genus Bacillus in 1872. In the twentieth century it became a model organism for genetics and sporulation, with its genome sequenced in 1997. Specific spore strains such as DE111 and HU58 were selected for supplement use only in the 2010s.

  1. 8th-11th c.Fermented-soybean tradition develops in Japan from Chinese douchi; the name natto emerges
  2. 1086-1088Legend ties natto's discovery to Minamoto no Yoshiie's northeastern campaign (straw-wrapped soybeans)
  3. 1835Ehrenberg describes the organism as Vibrio subtilis
  4. 1872Ferdinand Cohn renames it Bacillus subtilis and establishes the genus
  5. 1912-1926Taisho-era researchers develop a straw-free B. subtilis natto starter, enabling commercial natto
  6. 1997B. subtilis genome fully sequenced; it becomes a leading bacterial model organism
  7. 2019FDA files DE111 GRAS notice (GRN 831) without questions
  8. 2021Small Deerland-funded DE111 human RCTs (adults and children) and the ileostomy germination study are published

At a glance

Type
Spore-forming Bacillus
Found in
Soil, natto
Trait
Produces natural antibiotics
Strains
HU58, DE111

What this entry does not yet cover

What follows is unfinished work on our side, not a finding about Bacillus subtilis. A short entry is not a safe entry.

  • Cost and market. We have not documented what it sells for or who sells it.
  • Supply chain. We have not mapped where it is made.
  • Who uses it. We have not documented the user groups.
  • What could change. No forward-looking summary yet.
  • How it compares. We have not set it against the alternatives.
  • Children and teenagers. We have not checked what is known about younger people.

Sources