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Gram Stain?

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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Gram Stain?

Postby Bioslave » Wed Feb 27, 2008 2:19 am

What is the purpose of using iodine for the gram stain? thanks.
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Re: Gram Stain?

Postby blcr11 » Wed Feb 27, 2008 4:55 pm

It's a mordant. It forms an insoluble complex with the primary Gram stain, crystal violet or methylene blue, and helps keep the dye stay put once it has bound to wherever it binds. It probably also adds something to the color, but its main function is to keep the dye fixed to the sample.
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Postby Cat » Wed Feb 27, 2008 4:59 pm

Iodine (mordant) forms complex with crystal violet that cannot be washed out from gram +ve cells because of thick layer of peptidoglycan.
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Re: Gram Stain?

Postby Bioslave » Wed Feb 27, 2008 7:31 pm

thanks to both of you..

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