Anthrax: A Primer

Anthrax is caused by Bacillus anthracis. "Bacillus" is from the Latin word describing the rod (little staff) shape. "Anthracis" is from the Greek work for (black) coal. The bacterium has a cell wall of the gram-positive type. Gram-positive bacteria are usually susceptible to penicillin.

This bacterium makes endospores or "spores." Normally, when food is available, a bacterial cell grows and duplicates its chromosome, then the cell divides. The two daughter cells grow, duplicate their chromosomes and continue the cycle until the food it depleted or the environment no longer favors growth.

Instead of dividing into two daughter cells, Bacillus bacteria sometimes wall off the chromosome in a thick cell wall to produce an endospore. Vegetative cells have poor survival outside of an animal host, dying within 24 hours in water. However, the endospore can survive long periods of drought, heat, cold, toxic chemicals, and ultraviolet radiation. When a cell produces an endospore it is no longer reproducing but it will survive in an environment that kills the vegetative cells. During favorable conditions such as abundant amino acids and glucose found in animal blood or tissues, the spores germinate to produce a growing colony of cells.