Question

Why do some bacteria stain gram-positive or negative?

Answer 1

Bacterial staining:

1. Bacteria are free-living unicellular organisms that are found in every habitat.
2. Gram staining is the technique used to differentiate between bacterias based on their cell wall structures.
3. Gram-positive bacteria possess a thick peptidoglycan layer while gram-negative bacteria only have a thin layer of peptidoglycan.
4. Due to differences in peptidoglycan layer thickness, gram-positive bacteria retain the crystal violet stain while gram-negative bacteria lose the stain.
5. Thus based on the thickness of the peptidoglycan layer of the bacterial cells, they stain gram-positive or gram-negative.