∞ generated and posted on 2015.12.29 ∞
Means of differentiating microscopically between bacteria that have thick cell walls and no outer membrane from those that have thin cell walls and an outer membrane.
|Gram Stain or Gram Straining is the most common differential microbiological staining procedure and is used to differentiate so-called Gram-positive and Gram-negative bacteria, ones with thick cell walls versus thin and associated outer membrane, respectively.|
Gram staining is a kind of differential staining and utilizes a primary stain (crystal violet), mordant (Gram's iodine), a decolorizing agent (alcohol or acetone alcohol), and a counterstain (safranin).
Contrast for example the acid-fast stain as well as simple staining. See also Gram positive, Gram-positive cell wall, Gram negative, and Gram-negative cell wall.
Nice, animated overview of the Gram staining procedure:
The Gram staining procedure is presented without sound except for NPR playing in the background: ☺
Does a great job of showing how readily stain will splash during rinsing, though blot rather than the suggested heat drying following staining:
There in fact are quite a number of additional YouTube videos on Gram staining.