negative staining is when the micro-organism on slide is not stained.. instead the rest of the material on the slide gets stained and the organism stands out prominently unstained.. this occurs because that organism has a thick capsule around it which is non-stainable with that stain.. example is pneumococci staining with India ink.
size and shape
Because it is a Gram-negative bacterium and can be stained with Gram-negative stain.
Not all oral bacteria are gram negative, but those that are there can be seen with Gram 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.
It sometimes require additional chemical reagents to produce the desired action.
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Capsule Stain
size and shape
Because it is a Gram-negative bacterium and can be stained with Gram-negative stain.
Bacteria .
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.
Those which show pink colour in gram staining are gram negative bacterialike E.coli
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
Gram Negative
alcohol is organic solvent , it dissolves lipid in cell wall of Gram negative bacteria . this allows out flow of C.V. and counter staining by safranine which results in red color of Gram negative bacteria .
negative definition in health is an absents of an illness and disease.
Not all oral bacteria are gram negative, but those that are there can be seen with Gram stain.