In this simplified diagram of gram staining, bacterial cells are first treated with a purple dye called crystal violet. The dye gets into the cells’ peptidoglycan layer (gray), tinting it purple.

Gram-positive bacteria have thick cell walls. A Gram stain test, which involves a chemical dye, stains the bacterium’s cell wall purple. On the other hand, gram-negative bacteria stain pink instead.

The term “Gram” refers to a specimen staining method developed by Hans Christian Gram in 1884. It involves staining an organism with crystal violet or methylene blue dye and then observing the ...

Conversely, Gram-negative bacteria do not hold the dye well. Gram-negative bacteria may appear red under the microscope because red-pink iodine is used alongside the Gram stain as a control.

First, gram-negative bacteria have a thin cell wall that is about 1.5 to 10 nanometers across, whereas gram-positive bacteria ...

The Gram staining was first developed by a Danish scientist, Christian Gram, in 1884 and it has been used so far as the golden standard to classify bacteria. However, it has several obstructions.

Gram staining is a type of differential staining used to distinguish between gram positive and gram negative bacterial groups. ... before being counterstained with the red dye, safranin.

The Gram stain method – named after its inventor – consists in treating a smear of bacteria with a violet dye, then rinsing it with iodine solution and an organic solvent.