Negative Stain Results


Purpose:  To determine morphology, arrangement and size of bacteria, that may be affected by heat fixing.

Principle: The negative stain uses the dye nigrosin, which is an acidic dye.  By giving up a proton (as an acid) the chromophore of the dye becomes negatively charged.  Because the cell wall is also negatively charged only the background around the cells will become stained, leaving the cells unstained


 
Negatively Stained Bacillus: (A) Vegetative Cell  (B)  Endospore Negatively Stained Cocci

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