Pertaining to bacteria, holding the color of the primary stain (blue) when treated with Gram’s stain (a commercial staining agent), or Gentian violet solution. In contrast to the gram-negative bacteria, the gram-positive bacteria possess a much thicker peptidoglycan cell wall (capsule). Because of this, the blue crystal violet dye (with which the bacteria were stained) does not wash out of the cell and the bacteria appear blue under the microscope.
Retaining the color of the crystal violet stain in Gram’s method of staining.
When subjected to Gram’s stain, specific bacteria adopt a striking purplish-black shade.