Lab # 9 Structural Stains (Endospore, Capsule, and Flagella)

What are endospores also called? Why?

"resting bodies" because they do not metabolize and are resistant to heating, various chemicals, and may harsh environmental conditions

Many bacteria secrete chemicals that adhere to their surfaces, forming a viscous layer. What is this structure called?

A capsule when it is round or oval shape and a slime layer when it is irregularly shaped and loosely bound to bacterium.

What type of culture medium would increase the size of a bacterial capsule?

A medium that is rich in polysaccharides

Endospores are formed by several generea in what?

Bacillales and Clostridiales.

Describe the microscopic appearance of encapsulated Streptococcus if stained with safranin and nigrosin.

Bacteria would appear red, the capsule clear, and the background purple.

The flagella stain uses crystal violet, as does the Gram stain. Why do all cells stain purple in the flagella stain but not in the Gram stain?

Because the gram stain procedure uses a decolorizer in order to differentiate between Gran-negative and Gram-positive cells.

What are the Gram reactions of Clostridium and Bacillus?

Clostridium = Gram-positive; Bacillus= Gram-negative

Once an endospore forms in a cell, the cell wall will do what?

Disintegrate

After staining, endospores will be _________ in a red cell.

Green

How would an endospore stain in Mycobacterium appear?

Green

Motility can be determined by observing what two methods/preparations?

Hanging drop or wet mount preparations of unstained bacteria, flagella stains, or inoculation of soft (or semisolid) agar deeps.

Since endospores are impermeable to stains, what is done in order to drive the stain into the endospore?

Heat is applied.

Endospores are _____________ to stains.

Impermeable to stains

What stain do you cover the slide for the endospore stain?

Malachite green

________ stains flagella and increases their diameter.

Mordant

Flagella is the most common means of what?

Motility

Lophotrichous flagella

Multiple flagella coming out of one end (one pole)

Amphitrichous flagella

One flagella at each end of the bacterium (one on each pole)

Flagella are thin proteinaceous structured that originate in what and project from where?

Originate in the Cytoplasm and project from the Cell Wall.

Flagella are of two main types; what are they?

Peritrichous and Polar

Most capsules are composed of what?

Polysaccharides

What prevents the cell from appearing in the finished endospore stain?

The cells are easily discolorized and counterstain with safranin.

Endospores appear as colorless areas in a simple stain and Gram stain. Why is it necessary to perform an endospore stain to identify Clostridium difficile in health care settings?

The endospore stains would confirm it as an endospore.

Structural stains can be used to identify and study what?

The structure of bacteria

Of what advantage to Clostridium is an endospore?

They are dormant until conditions are stable and improve. They can also survive in harsh climates.

When are endospores formed?

When there is a lack of essential nutrients or water.

Peritrichous

all around the bacterium

Polar

at one or both ends of the cell.

Monotrichous flagellum

one flagella at one pole

How did the appearance of the 24-hour and 72-hour Bacillus cultures differ? How do you account for this difference?

the 24-hour culture had open spaces while the 72-hour one did not. In the 72-hour one, more endospores would have formed