Bacillus

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See Bacillus in Wikipedia, the free encyclopedia.

Bacillus, when capitalized, refers to any rod-shaped, gram-positive bacteria species of this genus. Uncapitalized, "bacillus" refers to any rod-shaped bacteria or archaea.

Bacillus bacteria are ecologically diverse. Most are free-living, facultative or obligate aerobes. Some are pathogenic, such as B. anthracis, the causitive agent of anthrax, and many are important for being food-spoiling organisms, or causing food-poisoning, including B. subtilus, B. cereus, and B. coagulans.

When stressed, Bacillus bacteria will produce endospores in order to go into dormancy. The endospore is, essentially, a dormant clone of the original bacterium that is protected by a thickened cell wall, and is retained within the body of the original bacterium. The bacterium, itself, dies once its environment worsens further, but, the now-liberated endospore is released. When the environment becomes favorable again, the endospore excysts and continues on its merry way. Generally, a Bacillus bacterium will only make one endospore at any one time.

An easy way to detect the presence of Bacillus bacteria is to take a piece of substance that is suspected of being contaminated, usually soil, and place it in mannitol salt agar. After a day of incubation at room temperature, spreading, irregularly-shaped Bacillus colonies will have appeared on the surface of the agar.

Some Bacillus species are utilized for economic and scientific purposes. B. subtilus is used extensively as an experimental organism, and its subspecies, B. subtilus natto, (sometimes refered to as B. natto) is used in Japan to ferment soybeans to make the snack "natto." B. thuringiensis is used as an insect control, thanks to the toxic crystals it produces with its endospore. Specific subspecies are used to control particular species of insect pests, particularly moth and mosquito larvae. Recently, though, there has been great concern that the use of B. thuringiensis in agriculture, and worse yet, the splicing of its toxin-producing genes into crops, may be a factor in the decline of non-pest insects, especially the Monarch butterfly, Danaus plexippus.