Pink Bugs, Purple Bugs

In 1884, Hans Christian Gram, a Danish doctor working in Berlin, accidentally stumbled on a method which still forms the basis for the identification of bacteria.
While examining lung tissue from patients who had died of pneumonia, he discovered that certain stains were preferentially taken up and retained by bacterial cells.

Over the course of the next few years, Gram developed a staining procedure which divided almost all bacteria into two large groups - the Gram stain.

In this experiment, you will:

  1. Learn the basics of microscopy.
  2. Perform the Gram stain procedure.
  3. Learn the structural basis which explains the existence of Gram-positive and Gram-negative bacteria.
  4. Identify some bacteria based on their appearance after Gram-staining.

Start the experiment

© AJC 2007.