Bacillus anthracis (Anthrax)

With Bacillus anthracis, bacillus means little rod and anthracis means coal.

So Bacillus anthracis is a rod-shaped bacteria that causes a disease called anthrax, that’s associated with characteristic black skin lesions.

Throughout history, Bacillus anthracis, or B. anthracis for short, has caused a number of plagues in Europe, and it’s also been used as biological warfare.

Not a good reputation!

Ok, now B. Anthracis has a thick peptidoglycan cell wall, which takes in purple dye when Gram stained - so this is a gram-positive bacteria.

Also, it is a non-motile bacteria and a facultative anaerobe, meaning it can survive with or without oxygen.

B. Anthracis is also a non beta-hemolytic bacteria, because when cultivated on a medium called blood agar, B. Anthracis colonies don’t cause beta-hemolysis, where hemolysis, or breakdown of the red blood cells that surround the colonies makes the blood agar change color from red to transparent yellow.

Finally, Bacillus Anthracis is a spore-forming bacteria, so it can undergo endosporulation when it feels threatened by the environment, like when the temperature becomes too high or too low, in case of extreme dryness, or when there’s harmful radiation around.

Endosporulation means that the bacteria starts by replicating its DNA, and then it forms a wall inside the cell, isolating the big portion of the cell, let’s call it the mother cell, from the small portion of the cell.

Next, the plasma membrane of the cell surrounds the newly formed small portion and then pinches it off, forming a separate body known as a forespore.

Next, the forespore gets completely engulfed by the mother cell, something like a cell within a cell.

Finally, inside the dying mother cell, the forespore loses water and accumulates calcium, and at the same time gets wrapped in a super tough cortex from the dying mother cell.

At this point, the endospore is able to resist heat, due to the presence of dipicolinic acid found in the core of the Bacillus anthracis spore, harsh chemicals, digestive enzymes, and even antibiotics.

Finally, as the mother cell dies off, the endospore is released outside.

Surprisingly, an endospore can last over a thousand years out, waiting for favorable conditions to come, and then germinate into the bacterial, or vegetative form, which can then grow, divide and infect organisms, causing anthrax.

In humans, anthrax can infect the skin, the lungs, or the gastrointestinal tract.