How can we distinguish between Gr+ & Gr- bacteria under the microscope?

Question

How can we distinguish between Gr+ & Gr- bacteria under the microscope?

Answer 1

From Wikipedia:

"Gram-negative bacteria are those bacteria that do not retain crystal violet dye in the Gram staining protocol. Gram-positive bacteria will retain the crystal violet dye when washed in a decolorizing solution. In a Gram stain test, a counterstain (commonly safranin) is added after the crystal violet, coloring all Gram-negative bacteria a red or pink color. The test itself is useful in classifying two distinct types of bacteria based on structural differences in their cell walls."

So, to answer your question, you need to apply a particular stain before distinguishing the two types under a microscope.

Answer 2

color... G(+) are purple  G(=) are red or pink