Natto: The Ultimate Source of Bacillus subtilis
Natto is a traditional Japanese food made by fermenting soybeans with the bacterium Bacillus subtilis var. natto. It is the most concentrated and well-known dietary source of this specific, beneficial bacterial strain. The process involves soaking and steaming soybeans, which are then inoculated with the natto bacillus and fermented at a controlled temperature for 16–24 hours. This fermentation gives natto its characteristic sticky texture, pungent aroma, and high nutritional value.
Beyond just providing probiotics, natto is exceptionally rich in vitamin K2 and nattokinase, an enzyme with potent fibrinolytic properties that supports heart health by helping to dissolve blood clots. For those new to its intense flavor and sticky consistency, natto is often mixed with soy sauce and mustard and served over rice. The fermentation process breaks down soy proteins, making them easier to digest and enriching the food with amino acids and other health-promoting compounds.
Other Fermented Soybean Products
While natto is the most prominent, other fermented soybean products also contain Bacillus strains, including B. subtilis, which contribute to their unique properties. These foods are staples in many Asian diets and include:
- Cheonggukjang: A pungent, traditional Korean soybean paste fermented primarily with Bacillus species at a high temperature for a short duration.
- Doenjang: Another Korean fermented soybean paste, doenjang is made from fermented soybean blocks (meju). Bacillus species, along with other microorganisms, drive this fermentation process.
- Miso: A traditional Japanese seasoning paste, miso is made by fermenting soybeans with salt and koji mold, but Bacillus subtilis strains are also naturally present.
- Thua Nao: A traditional fermented soybean food from Northern Thailand, similar to natto, where Bacillus species facilitate the fermentation.
These products vary in flavor, texture, and fermentation methods, but all rely on the activity of Bacillus strains for their unique characteristics and health benefits.
Fermented Vegetables and Grains
Bacillus subtilis is not limited to soy. Its hardy, spore-forming nature allows it to thrive in a variety of fermented environments. Korean kimchi, a spicy fermented cabbage dish, is known to contain Bacillus subtilis strains, among a diverse mix of other beneficial bacteria. Similarly, certain fermented products made from grains, like those in Chinese Daqu starters used for making liquors, also harbor Bacillus species. However, the concentration and role of B. subtilis can vary significantly compared to a targeted fermentation like natto.
Comparison of Bacillus subtilis Food Sources
| Food Source | Primary Ingredient | Fermentation Process | Notes on B. subtilis Presence |
|---|---|---|---|
| Natto | Soybeans | Inoculated with B. subtilis var. natto. Fermented for 16–24 hours. | High Concentration. Explicitly and intentionally fermented with a specific, potent strain. |
| Cheonggukjang | Soybeans | Cooked beans fermented with natural Bacillus species. | High Concentration. Fermentation relies heavily on Bacillus activity for its flavor and properties. |
| Miso | Soybeans, rice, barley, salt | Fermented with koji mold, but ambient Bacillus strains contribute. | Variable Concentration. Less concentrated than natto, but still a source. |
| Kimchi | Cabbage, seasonings | Spontaneous fermentation by naturally occurring bacteria. | Variable Concentration. A diverse bacterial ecosystem, including B. subtilis strains. |
| Kishk | Wheat, milk, yogurt | Traditional Egyptian fermentation of wheat and milk. | Variable Concentration. Natural fermentation process includes various bacteria, including B. subtilis. |
The Role of Spore-Forming Bacillus subtilis
The efficacy of Bacillus subtilis as a probiotic is partly due to its ability to form protective endospores. These spores are incredibly resilient, allowing them to survive harsh conditions like the high heat of food processing and the acidic environment of the stomach. Once they reach the intestines, these spores germinate, and the bacteria begin to colonize the gut and confer their health benefits. This resilience makes spore-forming B. subtilis strains ideal for both food applications and dietary supplements, as they are more likely to survive and deliver their probiotic effects than many other bacterial strains.
Conclusion
While probiotic supplements are a common and effective way to consume Bacillus subtilis, several traditional foods are natural, whole-food sources. Natto, a fermented Japanese soybean dish, stands out as the most concentrated dietary source. However, other fermented soy products like cheonggukjang, miso, and thua nao, along with fermented vegetables like kimchi, also contain varying amounts of B. subtilis. Including these fermented foods in your diet can be a delicious way to support your gut microbiome with this robust and beneficial probiotic. The natural fermentation process not only enriches these foods with probiotics but also enhances their flavor and nutritional profile.
What food has Bacillus subtilis in it? (Expanded)
For centuries, various cultures have unintentionally incorporated Bacillus subtilis into their diets through traditional fermentation techniques, harnessing its ability to thrive in specific food matrices like soybeans, grains, and vegetables. As a result, certain regional dishes, particularly from East and Southeast Asia, offer a natural and effective way to consume this potent, spore-forming probiotic. Though supplements provide a concentrated dose, these foods offer a complete nutritional profile that can contribute to overall gut and immune health. The distinct flavors, aromas, and textures of these dishes are a direct result of the metabolic activity of Bacillus strains during fermentation.
