Give an example of what could have happened if a known Gram negative sample looks like it is Gram positive? What about the inverse situation, where a known Gram positive sample looks like a Gram negative bacterial culture?

Question

Biology

Jude Hahn

8 June, 07:34

Give an example of what could have happened if a known Gram negative sample looks like it is Gram positive? What about the inverse situation, where a known Gram positive sample looks like a Gram negative bacterial culture?

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Answers (1)

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Gloria Kirk · Answer 1

Answer: Gram negative bacteria can appear gram positive if it is under decolorized I. e the alcohol is left for a very short time and the CV-I complex is not wash away, the bacteria can look like gram positive.

A gram positive bacteria can look like gram negative when it has been over decolorized, by allowing the decolorizing agent to stay too long on it or by using acetone.

Explanation:

Gram positive bacteria stained crystal violet when subjected to gram staining because it have cell wall composed of thick layers of peptidoglycan.

Gram negative bacteria have cell walls with thin layers of peptidoglycan and don't retain the crystal violet color when stained.