GRAM POSITIVE and GRAM NEGATIVE BACTERIA

	Gram-negative Bacteria	Gram-positive Bacteria
Gram reaction:	Can be decolourized to accept counter stain (Safranin or Fuchsine); stain red or pink, they don't retain the Gram stain when washed with absolute alcohol and acetone.	Retain crystal violet dye and stain dark violet or purple, they remain coloured blue or purple with gram stain when washed with absolute alcohol and water.
Peptidoglycan layer:	Thin (single-layered)	Thick (multilayered)
Teichoic acids:	Absent	Present in many
Periplasmic space:	present	Absent
Outer membrane:	Present	Absent
Lipopolysaccharide (LPS) content:	High	Virtually none
Lipid and lipoprotein content:	High (due to presence of outer membrane)	Low (acid-fast bacteria have lipids linked to peptidoglycan)
Flagellar structure:	4 rings in basal body	2 rings in basal body
Toxins produced:	Primarily Endotoxins	Primarily Exotoxins
Resistance to physical disruption:	High	Low
Inhibition by basic dyes:	High	Low
Susceptibility to anionic detergents:	High	Low
Resistance to sodium azide:	High	Low
Resistance to drying:	High	Low
Cell wall composition:	The cell wall is 70-120 Armstrong thick two layered.The lipid content is 20-30% (High), whereas Murein content is 10-20% (Low).	The cell wall is 100-120 Armstrong thick, single layered. The Lipid content of the cell wall is low , whereas Murein content is 70-80% (Higher).
Mesosome:	Mesosome is less prominent.	Mesosome is more prominent.
Antibiotic Resistance:	More Resistant to antibiotics.	More Susceptible to antibiotics