Differential Staining

Practice: A scientist is examining more than one species of bacteria under a microscope at the same time. The scientist decides to differentiate the bacterial cells based on their cell wall/cell envelope structure. Which staining technique should she use?

Practice: A scientist has a sample containing a variety of different bacteria species. She wishes to identify which bacteria in her sample are of the genus Mycobacterium. Mycobacterium have a wax-like, nearly impermeable cell wall which contains mycolic acid. Which type of staining technique should the scientist use to identify the Mycobacterium?