Question

Lab Supplemental Questions hital Questions Acid-Fast Stain 1. Why is acid-alcohol used as the decoloriting agent in the dio Aud-alcohol is used as the decolorizing Staining because it ensures that the pro form non acld fast organisme. agent in the acid-fast stain? orizing agent in the acid-fast the primary stain is removed 2. Why don't we Gram stain the mycobacterium? stain both acid-fast and non-acid-fast bacteria stain red, what 3. If at the end of the acid-fast stain both acid-fast and no technical mistake was made? It might be the mistake under decolonization .. 4. If at the end of the staining procedure Mycobacterium are staining procedure Mycobacterium are unstained, what mistake was made? for an organism 5. What cell wall properties are responsible for an organism staining acid-fast? - Mycolic acid B responsible Staring and fast? 6. Why is excessive decolorization very unlikely in the acid-fast stain but likely to occur in the Gram stain?

Answer 1

Answer 2) Mycobacterium’s cell surface has a waxy coat principally because of presence of mycolic acid. The coat makes the mycobacterium cells impermeable to gram stain as mycolic acid does not absorb the stain. Gram staining requires the presence of peptidoglycan (murein) in the cell wall.

Answer 4) The acid-fast stain was not prepared accurately.

Answer 6) When mycobacterium is stained by the acid-fast stain carbol fuchsin, it penetrates the cell wall which is rich in lipid content. This lipoidal layer prevents penetration of the decolourizing solution. Non-acid fast organisms or the organisms that take up gram stain lack any such lipoidal material and therefore can be easily decolorized.