The previous lab introduced simple staining techniques that enable microbiologists to observe the morphological characteristics of bacteria.  Although simple stains are useful, they do not reveal details about the bacteria other than morphology and arrangement.  The Gram stain is a differential stain commonly used in the microbiology laboratory that differentiates bacteria on the basis of their cell wall structure.  Most bacteria can be divided into two groups based on the composition of their cell wall: Gram+ and Gram-

This is The Most Important staining technique in Bacteriology.

• Gram Stain Theory
• Gram Stain Procedure