Essay On Gram Staining

INTRODUCTION There have been multiple staining techniques before the Gram stain came about in 1883. These old staining techniques brought about issues because they stained both the tissue and the cells so it was hard to differentiate between the two. Christian Gram is the inventor of the gram stain and found this technique when he was looking at Streptococcus pneumoniae in the lung tissue of people and animals (1). When working with these tissues, he found that this bacterium would take up a specific stain and leave the rest of the tissue decolorized There is an extra step that has been added, which is using a counterstain. Gram was not the one to come up with the counterstain and he never used it throughout his experiments (2). The counterstain came about a few years later when Carl Weigert used this technique. He realized using this counterstaining technique, that he would actually be able to see the cells that don’t keep the purple color. He used safranin, which is a red color. This would allow the bacteria that are not purple to turn pink in color. This was a way …show more content…
The primary stain uses crystal violet or methylene blue to stain the cells. Crystal violet will break into crystal violet (CV+) and chloride (Cl-) ions. These different ions will go through the cell wall and membrane of bacteria, which will stain them purple. The cells turn purple because the CV ions have a positive charge. This positive charge will interact with the negatively charged bacteria (4). This stain is left on the slide for 30 seconds and then washed off with water. Iodine is then added and it is known as the mordant. This forms a strong complex with the crystal violet. This complex is insoluble in water so the purple color will stay on the cell. This iodine is left on the slide for 60 seconds and then it can either be washed off by water or by