Peritrichous- Other Structures: Spores and Capsules. Why do you Why is it advant

Question

Peritrichous- Other Structures: Spores and Capsules. Why do you Why is it advantageous 1. Compare the spore staining of the 24-hour and "old" Bacilus cultures observe spores in the old culture but not in the 24-hour culture? for some organisms to produce spores? Spore stain: Why do you need to heat the slide for 5 minutes while you apply malachite green? 2. 3. What type of staining is used to visualize capsules? 4. What are capsules made of, and how might a capsule contribute to pathogenicity? 5. What are metachromatic granules? What are they composed of?

Explanation / Answer

1. Spores are produced by bacteria under nutrient deprivation conditions. The pores help the bacteria to survive these conditions. When they nutrients increase in the environment, the spores germinate or reproduce to form new organism. In the old cultures, the nutrients are completely utilized. Hence, the bacteria will form spores. In the 24 hour culture, there are still nutrients remaining. Hence, bacteria still do not form spores.

2) Spores are covered with keratin. This keratin will prevent malachite green from entering and staining the spores. The vegetative cell is easily stained without heat. Heat has to be applied for the malachite green to enter the spore.

3. Capsules are outermost covering in bacteria that surround the cell wall. Capsule is made up of polysaccharide. Capsules are stained by negative staining technique. Negative staining is a method that contrasts a translucent, darker colored, background with stained cells. The capsule is unstained. India ink or nigrosin or congo stain will stain the background. Methylene blue or crystal violet is taken up by bacteria. However, the capsule remains unstained.

4. Most capsules are made up of polysaccharide of repeating oligosaccharide units of two to four monosaccharides.. They are virulence determinants. Capsules are anti-phagocytic and limit engulfment by phagocytes due to their smooth nature and negative charge present on them. Bacterial capsule prevents the direct access of lysosome contents with the bacterial cell. They prevent complement-mediated bacterial cell lysis and protect anaerobes from oxygen toxicity.

5. Metachromatic granules or Babès-Ernst body or granule are composed of complex polyphosphate, lipid, and nucleoprotein molecules (volutin). They are intracellular phosphate reserves in a cell. They are formed during periods of phosphate uptake in a cell. They stain with a different color than the dye. They stain pink with methylene blue.

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