What is the difference between gram positive and gram negative bacteria?

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Bacteria are classified into gram positive and gram negative, the categories that are based on the composition and reaction of their cell walls to Gram stain test, developed by Hans Christian Gram. The differences between gram positive and gram negative bacteria are outlined in Table 1.

Table 1. The differences between gram positive and gram negative bacteria.

Features
Gram-negative
Gram-positive

Gram reaction
Stain red or pink and don&rsquo;t retain the stain when washed with absolute alcohol and acetone
Stain dark violet or purple and retain the stain when washed with absolute alcohol and water

Peptidoglycan layer
Thin
Thick

Outer membrane
Present
Absent

Toxins produced
Endotoxins
Exotoxins

Antibiotic resistance
More resistant
Less resistant

Cell wall
The cell wall is 70-120 &Aring; (&aring;ngstr&ouml;m) thick; two layered.
The cell wall is 100-120 &Aring; thick; single layered.

Features	Gram-negative	Gram-positive
Gram reaction	Stain red or pink and don’t retain the stain when washed with absolute alcohol and acetone	Stain dark violet or purple and retain the stain when washed with absolute alcohol and water
Peptidoglycan layer	Thin	Thick
Outer membrane	Present	Absent
Toxins produced	Endotoxins	Exotoxins
Antibiotic resistance	More resistant	Less resistant
Cell wall	The cell wall is 70-120 Å (ångström) thick; two layered.	The cell wall is 100-120 Å thick; single layered.

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