Source: Fondazione Diasorin
Level of schooling: high
Classrooms: 3, 4, 5
Date: 14-10-2020
Description
Gram staining, developed by the Danish doctor Hans Christian Gram at the end of the 1800s while studying the lung tissue of some patients who had died from pneumonia, is still widely used in microbiology laboratories today. It makes it possible to classify bacteria based on the cell wall’s composition and structure into “gram-positive” having a wall with a complex structure and rich in peptidoglycan, and “gram-negative” with a simpler structure and external lipid membrane. The staining in question is differential or contrast staining given that the bacteria are subjected to two consecutive staining cycles using different compounds and it is based on the bacteria’s varying ability to react to these compounds.
Downloads
See how to do this in your school laboratory following this protocol!
External links
Read a feature article on staining used in optical microscopy