Fermented Soybeans: A Primary Source of B. subtilis
When considering what food has B. subtilis in it, fermented soybean products are the most prominent and reliable sources. The most well-known of these is natto, a traditional Japanese food made by fermenting soybeans with a specific strain, Bacillus subtilis var. natto. The fermentation process results in the soybeans developing a distinct sticky, slimy texture and a pungent, nutty aroma. This process not only makes the soybeans easier to digest but also dramatically increases their nutritional value, including the production of vitamin K2 and nattokinase.
Fermented soybeans are a cornerstone of many Asian diets, and different countries have their own versions. For instance, in Korea, a similar fermented soy product is cheonggukjang, while in Nepal and Thailand, fermented soybean dishes are called kinema and thua nao, respectively. All these foods rely on Bacillus strains, often including B. subtilis, to drive their fermentation and create their unique properties. Research has shown that fermenting soybeans with B. subtilis also increases the bioavailability of certain nutrients and can produce flavor compounds.
Other Fermented Foods Containing B. subtilis
Beyond fermented soybeans, Bacillus subtilis is also present in other traditional fermented foods around the world, though its presence may be less common or associated with specific preparations. For example, some varieties of kimchi, the spicy Korean fermented vegetable dish, have been found to naturally contain B. subtilis. Egyptian kishk, a fermented dairy and grain product, is another traditional food where B. subtilis has been identified. The bacterium's hardy, spore-forming nature allows it to survive in various fermented environments.
While not all fermented foods contain B. subtilis, the inclusion of different bacterial strains, including various Bacillus species, is a hallmark of traditional fermentation methods. This natural bacterial diversity contributes to the unique flavors, textures, and health properties of these foods. However, the commercial production of modern fermented dairy products like yogurt and kefir typically relies on well-defined starter cultures of lactic acid bacteria, not B. subtilis.
B. subtilis in Supplements and the Environment
For many people, the most reliable source of Bacillus subtilis is through dietary supplements, which often use specific, well-researched strains like MB40 or DG101. These supplements offer a consistent and predictable dose of the probiotic, which is particularly beneficial for targeted digestive or immune support. As a soil-dwelling bacterium, B. subtilis is naturally widespread in the environment and in close association with plants, but this does not mean it is safe to consume directly from the ground. Instead, relying on properly prepared fermented foods or scientifically validated supplements is the safest way to gain the probiotic's benefits.
Comparing Food Sources: Natto vs. Other Ferments
| Feature | Natto (Fermented Soybeans) | Other Fermented Foods (e.g., Kimchi, Kishk) |
|---|---|---|
| Primary B. subtilis Source | YES. Explicitly fermented with B. subtilis var. natto. | Potential source, but presence depends on natural fermentation methods and specific preparation. |
| Reliability | Very high, as it is the defining microbe for the product. | Variable; depends on the specific product and traditional preparation. |
| Texture | Distinctively sticky and slimy due to the polyglutamic acid produced by B. subtilis. | Typically crunchy or mushy, but not slimy. |
| Flavor Profile | Pungent, earthy, and nutty. | Varies widely, but often sour, salty, and spicy. |
| Key Additional Nutrient | Vitamin K2 (menaquinone-7). | Varies by food; rich in Vitamin C and fiber in kimchi. |
| Ease of Consumption | Can be an acquired taste due to strong flavor and texture. | Generally more palatable to Western tastes. |
Conclusion
For those specifically seeking Bacillus subtilis in their diet, the clear winner is natto, the traditional Japanese fermented soybean dish, which uses a specific strain for its production. Other regional fermented soybean foods like Korean cheonggukjang and Thai thua nao also reliably contain Bacillus strains. While B. subtilis can also be found in certain preparations of foods like kimchi and Egyptian kishk, its presence is less guaranteed than in natto. For a consistent, high-potency dose, spore-based probiotic supplements are also a reliable option. Ultimately, incorporating fermented foods into a balanced diet can provide a range of beneficial bacteria, and choosing specific foods like natto can help target the inclusion of B. subtilis.
Foods with B. subtilis
- Natto: The traditional Japanese food is the most famous and reliable source, fermented specifically with Bacillus subtilis var. natto.
- Fermented Soybeans (Regional Variations): Similar to natto, Korean cheonggukjang, Nepalese kinema, and Thai thua nao are also made using Bacillus species.
- Kimchi (Some Varieties): Certain varieties of this Korean fermented vegetable dish, particularly those prepared with traditional methods, may contain B. subtilis.
- Kishk: An Egyptian fermented milk and grain dish known to include B. subtilis.
- Supplements: A common and reliable source, often containing specific, tested strains of B. subtilis for consistent probiotic intake.
