Capsule Stain (SPRING 2018 version) Introduction Some bacteria have a polysaccharide capsule. This can be seen with a microscope by making a Capsule Stain. Results + = Positive (clear "halos" around cells when viewed under oil immersion) - = Negative (no clear "halos" around cells when viewed under oil immersion) **** NOTE: this test can be hard to interpret and can sometimes give misleading results. Only use if absolutely necessary. **** Methods 1. Obtain two clean microscope slides. 2. Near one end of one of the slides (“first slide”), mix one drop of water with one drop of India ink (found on the back shelf). India ink stains the background (not the cells or the capsule). This is called a negative stain. 3. Aseptically add a small number of cells from your unknown stock culture into the water-ink drop, mix, but do not spread the drop. 4. Use the other slide to drag the water-ink-cell mixture into a thin film along the first slide (see * below if you would like a more detailed explanation – or ask your instructor). 5. Dispose of the second slide in disinfectant handling it with care as it contains live bacteria.
- Fall '18
- 45-degree, clean microscope slides