Which Bacillus species is nonmotile?

Which Bacillus species is nonmotile?

• A. Bacillus cereus
• B. Bacillus subtilis
• C. Bacillus anthracis
• D. Bacillus thuringiensis

Answer: (C)

Motility in Bacillus species is usually due to flagella, which lets the bacteria swim or swarm in semi-solid media. Bacillus anthracis is notable because it lacks these flagella, making it nonmotile. This absence of movement helps distinguish it from the motile relatives such as B. cereus, B. subtilis, and B. thuringiensis in diagnostic testing. In practice, motility tests can be used to separate the nonmotile B. anthracis from the motile Bacillus species in the lab, alongside other distinguishing features like its capsule and virulence factors.

Motility in Bacillus species is usually due to flagella, which lets the bacteria swim or swarm in semi-solid media. Bacillus anthracis is notable because it lacks these flagella, making it nonmotile. This absence of movement helps distinguish it from the motile relatives such as B. cereus, B. subtilis, and B. thuringiensis in diagnostic testing. In practice, motility tests can be used to separate the nonmotile B. anthracis from the motile Bacillus species in the lab, alongside other distinguishing features like its capsule and virulence factors.