![]() During this stage both the spore and vegetative cells appear as green in color. When taken from the steam bath followed by further cooling hardens the outer layer of the spore. This will soften the hard outer coverings of the spore and the primary stain gets stick to the spore. In Schaeffer-Fulton method, the primary stain, Malachite Green, is added over the heat fixed bacterial smear and heated over a steam bath for few minutes. The multiple thick coats of the spore made the endospore resistant to stain with most dyes. The endospore stain is used to determine the highly resistant spores of certain microorganisms within their vegetative cells. Special stains and mordents such as Leifson’s stain are required for staining the bacterial flagella.Įndospore staining is used to visualize specialized cell structures. The thin structures of the bacterial flagella make it difficult to observe under bright field microscope. Flagella are the thin delicate structure for bacterial motility. The metachromatic granules, the characteristic feature of Cornybacterium diphtheriae, can be differentiated from the bacterial cells with the help of Albert staining techniques. Specific stains such as nigrosine, Indian ink etc help to visualize the bacterial stains which cannot be stained by usual staining methods. Endospore staining is a special staining technique, to observe bacterial spores, where the spores take the color of the primary stain Malachite green, while the counterstain, safranin, give color to the non-spore forming bacteria. Other bacteria lose the stain and take on the subsequent color of the counter stain methylene blue stain and stain the cell as blue. Mycobacterium species due to its special cell wall resist the effect of the decolorizer acid-alcohol and retain the color of the primary stain carbolfuchsin stain and stains the acid fast cells in bright red color. Another differential staining technique is acid-fast technique which differentiates species of Mycobacterium from other bacteria. Gram stain technique is a differential staining technique, which separates bacteria into two groups (discussed in earlier chapters), Gram-positive bacteria and Gram-negative bacteria. ![]() In this technique the differential stains applied on the bacterial smear reveals the different types of cells at one point, reveals one part of the cell with one color and other parts a different color. The differential and cytological staining techniques discussed in this chapter help to differentiate between acid fast and non acid fast cells and to visualize the intracellular constituents of the microbial cells including endospores, capsules, metachromatic granules, and flagella. To study and gain expertise on differential and cytological staining techniques.ĭifferential staining is a technique that helps to characterize the microorganisms depending on the difference in the physical and chemical nature of the microorganism.
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