Week 2: Definitions

Chapter 4: Microscopy, Staining, and Classification

Differential stains: In microscopy, a stain using more than one dye so that different structures can be distinguished. The Gram stain is the most commonly used.

Here are three examples of differential stains that we discussed in class this week:

1) Gram stain: Technique for staining microbial samples by applying a series of dyes that leave some microbes purple and others pink. Developed by Christian Gram in 1884.

2) Acid-fast stain: In microscopy, a differential stain used to penetrate waxy cell walls.

3) Endospore stain: Differential stain which stains endospore or spore bacteria (Clostridium and   Bacillis).