Final answer:
The Gram staining technique involves staining bacteria with crystal violet, adding Gram's iodine, decolorizing with alcohol, and counterstaining with safranin, to differentiate bacteria based on cell wall properties.
Step-by-step explanation:
Gram Staining Procedure
The Gram stain procedure is a critical differential staining technique that aids in the classification of bacteria based on their cell wall composition. Initially, bacteria are fixed to a slide and stained with crystal violet. Next, Gram's iodine is applied, which acts as a mordant, binding the crystal violet to the bacterial cell wall. Subsequently, an alcohol solution is used as a decolorizing agent, which effectively removes the primary stain from gram-negative bacteria but not from gram-positive bacteria due to the differences in their cell wall structures. Finally, a counterstain, typically safranin, is added, imparting a pink color to the now colorless gram-negative cells, while gram-positive cells maintain the violet color.
Gram-positive bacteria, such as Staphylococcus aureus, retain the violet dye and appear purple under the microscope, whereas gram-negative bacteria like Escherichia coli appear pink. This technique is widely used in clinical laboratories to identify bacterial pathogens as part of the diagnostic process.