1. In gram stain if at the end of the procedure both the Gram-positive and Gramnegative...

1. In gram stain if at the end of the procedure both the Gram-positive and Gramnegative bacteria appear red what was the most common Technical error

2. In Gram stain you stop the procedure atter decolonization how would the Gram-negative bacteria appear? How would the Gram-positive

Expert Solution

Answer 1:

In gram staining procedure, during decolorization step, (i) crystal violet stain is retained by the thick peptidoglycan layer of gram positive bacteria, but (ii) it gets washed off in gram negative bacteria. In the next step, counterstain stains gram negative as red, whereas gram positive remain violet.

However, if the decolorization step is prolonged for too long, then it may remove the crystal violet stain out of gram positive cell wall also. Thus, when counterstain is applied, both gram positive and gram negative get stained as red.

Answer 2:

If we stop the Gram staining procedure after decolorization step, then:

Gram positive bacteria would appear violet (bluish) in color.
Gram negative bacteria would appear colorless, as it looses the crystal violet stain.

Note:

Gram positive bacteria has a thicker peptidoglycan layer as the outermost layer, whereas Gram negative bacteria has a thinner lipopolysaccharide layer as the outermost layer.

(kindly upvote if the answer was helpful.)

gladiator answered 2 years ago

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