Difference between gram negative & gram positive species?

Answer 1

There is a difference in the surface of the cell walls that make these cells accept gram stain ...a wavy surface versus a smooth surface. The wavy surface of the gram positive absorbs the stain and the smooth surface of gram negative repels the stain...In this way the lab can test for gram negative or gram positive.

See these two pages for more info !


http://medic.med.uth.tmc.edu/path/00001443.htm

http://medic.med.uth.tmc.edu/path/00001444.htm

Answer 2

Bacterial cell walls are responsible for the properties that give rise to either gram negative or gram positive organisms. Both types of bacteria produce a cell wall that contains peptidoglycan, but gram positive organisms generate a very much larger cell wall than do gram negative. So, during the gram stain procedure only those organisms with the very large cell wall will retain the blue stain that makes them gram positive.

Answer 3

"Gram positive" bacteria, the ones that turn purple during staining, have a thick wall made of peptidoglycan, which soaks up the stain. Other bacteria, "gram negative," have a thinner peptidoglycan wall that is covered by a membrane, which prevents staining.
As a side note, this is why we have "broad spectrum" antibiotics, they fight infection from both gram negative and gram positive. Older drugs, like penicillin, works best against gram positive but aren't so good against gram negative.