What is Gram Staining?

Gram staining is a procedure used to distinguish Gram positive bacteria from Gram negative bacteria.

Steps:

• In the beginning, both Gram positive and Gram negative bacteria look alike. So, they are unstained.
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• Crystal violet is used in the next step, both Gram positive and Gram negative bacteria become violet in color.
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• In the third step, Iodine is used to stain. Both look alike i.e., violet in color.
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• Now, bleaching is done with the help of acetone. After bleaching, Gram positive bacteria look violet and Gram negative bacteria contain no color.
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• In the last step, both are stained with Safranin -- Gram positive bacteria get purple color while Gram negative bacteria get red color.

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