In Gram stain procedures, what does Safranin do?

In Gram stain procedures, Safranin functions as the counterstain that colors the bacteria that are Gram-negative. After the initial staining with crystal violet and the subsequent application of iodine, which acts as a mordant, the bacteria are decolorized with alcohol or acetone. This decolorization step removes the crystal violet from the Gram-negative bacteria, which do not retain the primary stain due to their thinner peptidoglycan layer. Safranin is then applied, providing a contrasting red or pink color to these decolorized Gram-negative bacteria. This contrast allows for differentiation between Gram-positive and Gram-negative organisms under a microscope.

The role of Safranin is crucial because it enables the visualization of Gram-negative bacteria after the decolorization step, ensuring that the entire Gram stain process facilitates the identification of various bacterial types based on their cell wall structure.