Comparison: Gram positive bacteria and Gram negative bacteria

Gram positive bacteria	Gram negative bacteria
1.     The bacteria remain coloured with Gram staining even after washing with alcohol or acetone	The bacteria do not retain the stain when washed with alcohol or acetone. So these type of bacteria are observed with another stain such as safranin.
2.     Outer membrane is absent	Present
3.     Thicker cell wall. Thickness varies from 20-80 nm	Thin cell wall. Thickness varies from 8-12 nm
4.     Smooth wall	Wavy wall and comes in contact with plasma membrane only at a few loci.
5.     The wall contains 70-80% peptidoglycan (murein or mucopeptide)	The wall contains 10-20% peptidoglycan
6.     Teichoic acids may be present	Teichoic acids absent
7.     Very little lipid content (0-2%)	High lipid content (20-30%)
8.     Lipopolysaccharide layer (LPS) absent.	Present
9.     Basal body of the flagellum contains 2 rings	Basal body of the flagellum contains 4 rings
10.  Mesosomes are quite prominent	Mesosomes are less prominent
11.  A few pathogenic bacteria belong to Gram positive group	Most of the pathogenic bacteria belong to Gram negative group
12.  E.g. Bacillus subtilis, Mycobacterium, Noccardia	E.g. Escherichia coli