This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Bacillus anthracis is unique to other bacteria. It is the only bacteria to possess which of the following 
Select and explain. 
A. A polypeptide capsule, B. A polysaccharide capsule, C. An exotoxin, D. An endotoxin
A: A polypeptide capsule
Answer: A: A polypeptide capsule 
Explanation: Virulent forms of B. anthracis, the causative agent of anthrax, are more likely to be surrounded by a capsule. This capsule is a polypeptide, composed of a polymer of glutamic acid, and is a unique feature of B. anthracis. Lipopolysaccharides (LPS/endotoxin) are unique to gram-negative bacteria (B. anthracis is a gram-positive rod). In addition, whereas B. anthracis is associated with both teichoic acid (cell wall) and a potent exotoxin, these are not unique features of this bacterium. Other gram-positives (i.e., staphylococci) release exotoxins and have teichoic acid in their cell walls.