BIO 22 Lab Quiz #7: Endospore Stain

What is a bacterial endospore & what is its purpose?

A bacterial endospore is a structure formed within a bacterium that is resistant & dormant. The endospore's purpose is to protect the bacterium from poor or unfavorable conditions that hinder its survival. Spores are also resistant to heat & chemicals that would otherwise kill other bacteria.

List two genera of bacteria that produce endospores.

Bacillus & Clostridium.

Why are endospores important from a clinical viewpoint?

Endospores are especially important from a clinical standpoint because they are very resistant to processes or antibacterial methods that would normally kill off vegetative cells. This means that they are particularly difficult to kill. Endospores allow the bacterium to create a resistant & dormant cell that can preserve the original cell's genetic material when put under extremely unfavorable conditions.

What causes some bacteria to produce endospores?

Sporulation / sporogenesis occurs in bacteria when a key nutrient like carbon or nitrogen, becomes unavailable or scarce. This leads the bacteria to create an endospore that can survive in the conditions that the original could not.

What affect does the age of the culture have on endospore production?

The age of the culture is important for endospore growth. Endospore-forming bacteria cannot uniformly grow endospores when a culture is new & growing. Endospores can only be formed in response to a scarcity of nutrients, which can only occur in older cultures.

What color will the spores be after performing the endospore stain?

The endospores should stain green.

Why does the smear need to be steamed when applying malachite green to the slide?

The smear needs to be steamed because this allows the stain to penetrate the wall of the endospore.

What color will the vegetative cells be after performing the endospore stain?

The vegetative cells should appear red or pink.