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Acidic dyes are negatively-charged dyes. Since bacteria are also negatively-charged, they will repel the acidic dyes. So, instead of staining the bacterium itself, it will be the background that will be colorized....
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What is a negative stain?
The negative staining techniques uses a dye solution in which the chromogen is acidic and carries a negative charge. (An acidic chromogen gives up a hydrogen ion, which leaves it with a negative charge.) The negative charge on the bacterial surface repels the negatively charged chromogen, so the the cell remains unstained against a colored background.
What are the advantages of the simple stain technique over the negative stain technique?
Negative staining has a dark contrasted background and the bacteria is white. Simple staining has a white background and bacteria is the color depended on your stain color.Negative staining when prepared is NOT heat fixed but simple staining when prepared is heat fixed. Heat fixed means when preparing slide with bacteria on it, it is passed over some type of flame, like a Bunsen burner flame, three times or four times.
Is safranin an acidic dye?
Sure, any basic stain can be used for simple, direct staining.
What is the name of the paper used to dry slides after gram staining?
Gram staining is used to identify whether a bacterium is gram positive or gram negative. Slides can be dried using filter paper or tissues. The technique is based on the reaction of stain that happens with the membrane of bacteria.
Is carbol fuchsin the same as safranin?
No. safranin is the classic stain used in gram staining. Concentrated Carbol Fushin is mainly used for the ZN staining procedure to stain organisms such as Vibrio cholerae and Cryptosporidium. Diluted Carbol Fushin can however be used as a replacement counterstain for Safranin in the gram stain.
What is a negative stain?
The negative staining techniques uses a dye solution in which the chromogen is acidic and carries a negative charge. (An acidic chromogen gives up a hydrogen ion, which leaves it with a negative charge.) The negative charge on the bacterial surface repels the negatively charged chromogen, so the the cell remains unstained against a colored background.
Why cant methylene blue be used in place of nigrosin in negative staining?
Because negative staining requires the use of an acidic stain, which will not penetrate the cells because of the negative charge on the surface of the bacteria. As a result, the unstained cells can be easily identified against the colored background.
Why is the technique called negative staining?
Because the cell wall repels the binding of the negative stain therefore the cells do not stain. Because of this the background is stain with the dye used and the bacteria remain colorless. Basically your staining the background, that is, you are not directly staining the cells.
Describe the microscopic appearance of encapsulated streptococcus if stained with safranin?
Safranin (red) is used in gram staining and endospore staining as the secondary stain. Nigrosin is used in negative staining, staining only the background and not the bacteria. Therefore, the bacteria within the capsule would stain red from the safranin. (Like in endospore staining and negative gram staining, safranin would stain the bacteria red.) Nigrosin would stain the background of the organism just as it would in negative staining. Bacteria (within capsul): stained safranin red Capsule (outer layer of bacteria): clear Background of organism: stained dark with Nigrosin
What are the advantages of the simple stain technique over the negative stain technique?
Negative staining has a dark contrasted background and the bacteria is white. Simple staining has a white background and bacteria is the color depended on your stain color.Negative staining when prepared is NOT heat fixed but simple staining when prepared is heat fixed. Heat fixed means when preparing slide with bacteria on it, it is passed over some type of flame, like a Bunsen burner flame, three times or four times.
Is safranin an acidic dye?
Sure, any basic stain can be used for simple, direct staining.
What is secondary stain?
A secondary stain is Methylene blue. This type of stain is used in a acid fast staining. This type of staining test can determine medical conditions such as tuberculosis.
What does a negative result for a spore stain indicate about the organism?
A negative result for the spores stain indicate that the gram-negative organism is present. A positive result for a spore stain indicates that a gram positive organism is present.
What counter stain is used in gram staining?
safranin
What mordant is used in spore staining?
Heat is the mordant used in the spore stain, it fixes the primary stain.
What is the purpose of differential staining?
differential staining is a staining technique used to stain colorless bacteria against a dark background.
Why is size more accurate in an acidic or negative stain than in a simple or basic stain?
Since there is no heat fixing or strong cemicals are used the bacteria are less distorted
