4. Predict the effect of heat-fixing the bacteria on a slide that you plan to st

Question

4. Predict the effect of heat-fixing the bacteria on a slide that you plan to stain with nigrosin 5. Predict the effect of the following mistakes when performing the acid-fast staining protocol A. Failure to heat the slide during addition of the primary stain. B. Decolorizing with acetone-alcohol instead of acid-alcohol. C. Staining the cells with methylene blue first and carbolfuchsin second. 6. Consid er the endospore staining protocol when answering the following questions A. What two genera of bacteria can form endospores? 8. Under what conditions do endospores typically form? In other words, what causes bacteria to form endospores? C. Last semester when performing the endospore stain on a sample of Bacillus laterosporus I saw almost no spores despite looking at hundreds of cells. Suggest three possible explanations for this result. 1. 2. 3. D. Predict the appearance of spores in cells that have been stained for 1 minute with malachite green, washed, then counterstained with safranin for 1 minute.

Explanation / Answer

Answer :-

4. Nigrosin is an acidic stain. Since the surface of most of the bacterial cell wall is negatively charged, so the cell surface of the bacteria will repel the stain. As stain having negatively charged functional groups so they can't bind to tsh negatively charged bacteria.

5.

(a) Failure to heat the slide during the addition of the primary stain means there will be no penetrative of stain. As heat applied to the primary stain so as to penetrate the stain.

(b) Decolorizing with acetone alcohol instead of acid alcohol means that they will not be able to resist Decolorization because acid bacteria having waxy substance known as mycolic acid present in their cell walls which makes them impermeable to many stains. In case of acid alcohol, they are able to resist Decolorization.

(c) Staining the cells with methylene blue first and carbolfuchsin second made impossible to differentiate bacteria of acid fast group and non acid fast group.

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