|
The Gram-Negative Cell
UnlikeGram-positive
bacteria, which asuume a violet color in Gram
staining, Gram negative bacteria incorporate the counterstain rather
than the primary stain. Because the cell
wall of Gram(-) bacteria is high in lipid content and low in
peptidoglycan content, the primary crystal-violet escapes from the cell
when the decolorizer is added. This is because primary stains like to bind with
peptidoglycan- something the G(-) cell has very little of. Gram(-) bacteria
cause a lot of problems because many species are pathogenic. This pathogenic
capability is usually associated with certain components of their cell walls,
particularly the lipopolysaccharide (endotoxin) layer. Remember
the Black Plague which wiped out a a third of the population of Europe? It was
caused by the tiny G(-) rod, Yersinia pestis. Most enteric
(bowel related) illnesses can also be attributed to this group of bacteria. Some
of my favorites are Salmonella food poisoning.
|
