Differences between Gram positive and Gram negative bacteria

S.N Gram positive bacteria Gram negative bacteria
1 They retain the crystal violet stain during gram staining. They do not retain the crystal violet stain during gram staining.
2  Cell wall is simple. Cell wall is complex.
3 They appear blue/purple. They appear pink/red.
4 The thickness of wall is 20-80 nm. Thickness of wall is 10 nm.
5 They have thick peptidoglycan  cellwall layer (>50%). They have thin peptidoglycan layer (10-20%).
6 Outer lipopolysaccharide wall layer is absent. Outer lipopolysaccharide wall layer is present (13%).
7 Cell wall is very rigid and less elastic. Cell wall is less rigid and more elastic.
8 Teichoic acid is present. Teichoic acid is absent.
9 There is no protein content. There is protein content.
10 Periplasmic space is absent. Periplasmic space is present.
11 Porins are absent. Porins are present.
12 s- layer is attached to the peptidoglycan layer. s- layer is attached to the outer membrane.
13 Mesosomes are more prominent. Mesosomes are less prominent.
14 They produce endospores during unfavourable condition. They do not produce endospores  usually.
15 They produce exotoxins usually. They produce endotoxins usually.
16 They show high tolerance towards dryness. They show less tolerance towards dryness.
17 Muramic acid content of cell wall is more in these group (16-20% of dry weight). Muramic content of cell wall is less (2-5% of dry weight).
18 Examples: Bacillus subtilis, Streptococcus, Clostridium

 

Gram positive bacteria after Gram staining

 

 

Examples: E. coli, Rhizobium, Vibrio, Acetobacter

Gram negative bacteria after Gram staining

Differences between Gram positive and Gram negative bacteria

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