Bacillus Subtilis: Characteristics & Arrangement

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  • 0:00 What Is Bacillus Subtilis?
  • 0:39 Characteristics
  • 2:56 Metabolism
  • 3:27 Why B. Subtilis Is Important
  • 5:02 Lesson Summary
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Lesson Transcript
Instructor: Erika Steele

Erika has taught college Biology, Microbiology, and Environmental Science. She has a PhD in Science Education.

This lesson will discuss the characteristics of the bacterium Bacillus subtilis, including its microscopic characteristics, its metabolism, and its use by humans.

What Is Bacillus Subtilis?

Sometimes the bad guys in a movie are the ones you remember, and the good guys, though essential or useful, are kind of boring. Bacillus subtilis, a bacterium that belongs to the genus Bacillus, is like that good guy.

Unlike its bad guy cousins Bacillus anthracis (which causes anthrax) and Bacillus cereus (which can cause food poisoning, B), subtilis doesn't cause disease in humans or animals. It just hangs out in hot soil and in the guts of animals like cows and humans.

Even though this bacterium isn't associated with a disease, it does have some pretty cool adaptive features and uses in science.


Like all members of the genus Bacillus, B. subtilis is a rod-shaped bacterium that typically forms small clumps, short chains, or single cells. It has a cell wall that is made of a complex molecule called peptidoglycan, which is made of long chains of glucose linked together by amino acids. Peptidoglycan surrounds the cell membrane and gives the bacterial cell shape and structure.

Bacteria can be differentiated by the thickness of the peptidoglycan layer using a specialized stain called a Gram stain. Using the Gram stain procedure, the cells of B. subtilis would appear purple because they have a thick layer of peptidoglycan in their cell wall. Cells with a thick peptidoglycan layer are called Gram-positive.

Like all bacteria, B. subtilis has a single circular chromosome that is located in the nucleoid region of the cytoplasm. Even though B. subtilis doesn't cause an interesting disease like anthrax, its chromosome does contain genes that produce useful antibiotics and compounds that can be used in bioremediation, which is a process that uses microorganisms to clean up the environment.

Racing is one thing at which B. subtilis can beat its anthrax-causing cousin. B. anthracis is non-motile, while B subtilis is very motile. Most bacteria that can move, including B. subtilis, use flagella, which are long, whip-like tails. B. subtilis has peritrichous flagella, meaning the cell is covered in little tails. These flagella tails are observable with a light microscope using a specialized stain.

B subtilis forms endospores, which are tough, dormant structures produced by some bacteria in a process called sporulation. Endospores are resistant to heat, drying, radiation, freezing, disinfectants, and other conditions that would normally destroy bacteria. When conditions are bad, the bacteria will store the chromosome in the core of the endospore, allowing it to survive until conditions are favorable.

Living organisms have been revived from endospores that are 100s of years old. That is a pretty cool adaptation to have even if you are the boring cousin in the family. It's like carrying around your own cryogenics machine, so you can freeze yourself and reanimate later!


All organisms have to get nutrients and energy in some way. B. subtilis is a heterotrophic organism, which means it can't make its own food so it has to eat or consume something just like we do. B. subtilis absorbs its nutrients from the environment: those nutrients have to be converted into energy in some way. While humans and some other types of bacteria require oxygen to convert nutrients into energy, B. subtilis can make do without. Organisms that do not need oxygen to make energy are called facultative anaerobes.

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