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Gram Staining: Gram positive and Gram negative bacteria

Updated on October 2, 2013

One of the most important cytological features of bacteria is their reaction to a simple procedure called, after its discoverer, the Gram stain. The cell wall of bacteria shows a characteristic reaction to the gram stain devised by C. Gram.

Gram Staining Procedure

Gram Staining Procedure
Gram Staining Procedure | Source

The gram staining procedure involves staining cells with the dye crystal violet and all the bacteria will be stained blue. The bacteria are then treated with an iodine solution and decolourized with alcohol. Those bacteria which retain stain are known as Gram positive and those which do not retain the stain are termed as Gram negative. This is the fundamental difference between gram positive and gram negative bacteria.

Gram positive
Gram positive
Gram negative
Gram negative

Difference between Gram Positive and Gram Negative Bacterial Cellwall

Bacterial Cell wall
Bacterial Cell wall
Character
Gram positive
Gram negative
Number of layers
One
Two
Thickness
Thick(20-80nm)
Thin (8-10 nm)
Outer membrane
Absent
Present
Periplasmic space
Present in some
Present in all
Chemical composition
Petidoglycan, Teichoic acid and lipotechoic acid
Lipopolysaccharide, lipoporteins and peptodoglycan
Peptidoglycan
More
Less
Porins proteins
Absent
Present
Lipid
Less
More
Amino acids
Striking simplicity of amino acids. Glutamic acid and alanine occur in large amounts
All the amino acids are present
Muramic acid
More
Less
Permeablilty of molecules
More penetrable
Less penetrable
Resistance to molecules
Less
More

List of Gram Negative bacteria

  • Escherichia coli (E.coli)
  • Helicobcater
  • Hemophilus
  • Neisseria
  • Cyano bacteria
  • Klebsiella
  • Acetobacter
  • Enterobacter
  • Chlamydia
  • Vibrio
  • Pseudomona
  • Salmonella
  • Thiobacter
  • Borrelia
  • Burkholderia
  • Serratia
  • Treponema

List of Gram Positive Bacteria

  • Bacillus
  • Nocardia
  • Clostridium
  • Propionibacterium
  • Actinomyces
  • Enterococcus
  • Cornyebacterium
  • Listria
  • Lactobacillus
  • Gardnerella
  • Mycobacterium
  • Mycoplasma
  • Staphylococcus
  • Streptomyces
  • Streptococcus

How gram staining works?

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    • rajan jolly profile image

      Rajan Singh Jolly 4 years ago from From Mumbai, presently in Jalandhar,INDIA.

      Excellent and interesting. Thanks for this lesson.

      Voted up & interesting.

    • deenahere profile image
      Author

      Deena 4 years ago from India

      Rajan Jolly

      Thanks for your visit and comments.

    • profile image

      rajiv kumar 4 years ago

      Excellent & essy thnks

    • profile image

      vinay 3 years ago

      Thanks for this notes

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