Use your sterile inoculating loop to transfer a colony from the culture plate that corresponds with the slide you just prepared,
and gently mix the microbes with the nigrosin.
4. Place the clean slide at about a 45° angle next to the nigrosin, and use the slide to gently spread the dye over the specimen
(Figure 10).
Figure 10: Use a clean slide set at a 45˚ angle to spread the nigrosin across the slide.
5. Repeat Steps 1 and 2 with the second “Negative” slide.
6. Air-dry the dye-stained samples for approximately 10 minutes.
7. If you have a microscope available, observe the stained slide
under increasing the magnification, and record what you see at
each magnification in Table 2 focusing on morphology and ar-
rangement of the cells utilizing terms learned in this lab. If there
is no microscope is available, refer to Figure 11 and take a photo-
graph of your slide if required by your instructor. If keeping a lab
notebook, print out Table 2, and tape it into your lab notebook, or
re-create it by hand.
Figure 11: Isolated bacteria negatively stained with nigrosin. Image credit Rieg et al., 2010 (https://wwwnc.cdc.gov/eid/article/16/3/09-1457_article)
8. Place your slide in a disposable plastic container, and pour
bleach over the surface until the sample is completely covered/
saturated. Allow the sample to soak in the bleach for approxi-
mately 20 minutes, and then rinse the bleach down the sink with running water.
9. Wrap the bacterial slide in Parafilm®, and dispose of it in the trash.
Data SheetExperiment 2 Data Sheet Table 2: Experiment 2 Staining Observations
Stain Used:
Observations:
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