Gram Staining Procedure and its Details

Gram Staining Procedure and its Details

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  • Gram staining procedure was discovered by Han’s Christian Gram in 1884.
  • Gram staining is a universal staining technique used for identification and classification of organisms.
  • In this staining, method bacteria are classified into two groups that are-

                                                                        1. Gram-positive bacteria

                                                                        2. Gram-negative bacteria

  • This classification of bacteria depends upon the property of a cell to retain or lose the primary stain after the treatment of decolourising agent. 
  • Gram staining is a basic and widely used technique.
  • This technique was modified by many scientists but the best result was obtained by Hucker and Conn’s modification.


  1. A clean grease free slide.
  2. Bacterial cell suspension.
  3. Nichrome Wire loop.
  4. Primary stain – Crystal violet.
  5. Mordant- Gram’s Iodine.
  6. Decolourising agent- 95% alcohol ( 95% Ethanol).
  7. Counterstain- Basic fuschin or Safranin.

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