2. Introduction
I. Gram stain is the most important used stain in Bacteriology lab.
II. It used to differentiate between gram positive bacteria and gram
negative bacteria.
III. The difference between gram positive and gram negative is
the ability of cell membrane to retain crystal violet.
3. In gram-positive bacteria, the thick layer of
peptidoglycan (which form the outer layer of
the cell membrane) retain crystal violet
color.
4. Method
(1)
Bring Section
To Water
(2)
Flood the slide
with crystal
violet
3 minutes
(3)
Flood the slide
with Iodine
2 minutes
(4)
Wash with tap
water
(5)
Flood the slide
with Acetone
10 sec
(6)
Wash with tap
water
(7)
Flood the
slide with
Safranin
30 sec
Wash in tap water, keep in oven for 1-2 minutes, clear and mount!
