Negative Stain
Why didn't you heat fix the bacterial suspension before staining?
Heat fixation is not used in negative staining because the goal of the experiment is to view bacteria that has not been distorted by harsh staining or heat fixing. Heat fixing shrinks cells!
What is an advantage of negative staining?
The advantage of negative staining is that you are able to view the cells without risk of them being damaged or distorted as they might be with a positive stain. The dark stained background provides contrast making it easier to view the bacterial.
Why is negative staining also called either indirect or background staining?
Negative sating is also known as indirect or background staining bc it ors not directly stain the bacterial cells rather it indirectly stains them by coloring the background making the cells more easily viewable.
When is negative stain used?
Negative staining is used when it is important to be able to view the bacteria without using harsh stains or performing the heat fixing technique that could possibly distort or change the shape of the bacteria. It is used when looking at capsules and yeast or spirochetes that do not stain well. Negative stain is used when viewing bacteria by wet mount or hanging drop slide to view bacterial motility.
why do bacteria remain unstained in the negative staining procedure?
Negative stains will not penetrate and stain the bacterial cell wall because they have a negative charge and therefore are repelled by the negative charge of the bacterial cell. The stain will produce a deposit around the bacteria or produce a dark background making the bacteria appear to be clear or unstained.
Name 3 stains that could be used from negative staining.
Nigrosin india ink eosin
When streaking with the second slide, why must it be held at a 45 deg angle?
When streaking with the second slide it is important to hold the slide at a 45 deg angle so that the bacteria nigrosin solution spreads across the edge of the slide that that you can get a tin smear. The smear is thick on one end and thinner towards the middle.
