Bacillus is a genus of Gram-positive, rod-shaped bacteria that is found widespread in the environment. As a result, they are often called “soil organisms” or "soil bacteria", although they can be found in soil, water, dust, air and feces. This genus is composed of approximately 77 very different species of bacteria.
Some, but not all, of the species are:
What makes these microbes unusual in the beneficial bacteria probiotics world is that the bacteria form endospores under stressful conditions. These endospores have tough outer coatings that protect the dormant bacteria inside.
This protection can last for years and can be resistant to extreme heat, radiation, extreme freezing, drying, and chemical disinfectants. When conditions are favorable for growth, the endospore converts to a vegetative cell which can thrive.
Most, but not all, of these bacteria are motile, meaning they can independently move, thanks to a whip-like appendage called a flagellum.
This species of bacteria is in the same class of microbes as Lactobacillus, so some genes are common between the two species.
Spores of Bacillus bacteria are regularly consumed by animals and humans inadvertently through their foods and drinks and in some fermented foods. There is some concern that although these spores may be regularly consumed accidentally, intentionally taking billions of them everyday as probiotics floods the intestines and may lead to an unnatural state in the intestines since they are not resident bacteria.
Although many effects of this genus of bacteria is not only species-dependent, but also strain-dependent, one important commonality among the bacteria in this genus is that they can stimulate the immune system. This may be good or bad, depending on the circumstances.
Additionally, the genus Bacillus is known to be able to acquire plasmids from other bacteria in the environment. These plasmids can be harmless or may contain information for antibiotic-resistance or toxin production. Also, some species of Bacillus used as probiotics have antibiotic resistance, so you would want to inform your healthcare provider if you are taking them.
It used to be thought that the spores of the probiotic Bacillus species passed through the stomach and germinated in the small intestine into vegetative cells which, in turn, changed back into spore form once they reached the colon where they were then eliminated. It is now known that the processes are more complicated:
The most important thing to know about Bacillus probiotics is that identification of the strain is very important because mislabeling occurs.
Some of the famous and infamous species include:
Since this site is about probiotics, more information can be found on these species:
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