Microorganisms are playing a major role Eco system, especially in medicinal field and industries. So the visualization of microbe is one of the major steps in the troubleshooting process. When we view the bacteria under a microscope it will be colourless, because the lack of contrast. So that concern staining of bacteria is must.

There are several types of staining techniques, depends on the need the we can do any of the staining process. Staining process also involves heat fixing & drying.

1.Simple Staining

First & the basic staining method is simple staining. In this method basically we can use basic dyes like Methylene blue or Basic fuchsin. It will give the colour to the bacteria.

2.Negative Staining

Negative staining is nothing but opposite to simple staining means in this method we would stain the background of the bacteria & the bacteria kept unstained. This method is useful to demonstrate the bacterial capsules & some other bacteria that are not demonstrated by simple staining. In Negative staining, we can use Indian Ink or Nigrosin.

3.Differential Staining

The third & the most important staining technique is differential staining. In differential staining the bacteria will be stained with different colour. The two major & the most widely used techniques of differential staining are Gram staining & Acid fast staining.

Gram staining

    In 1884, Hans Christian Gram discovered this gram staining method. He stains the bacteria by using this method. The precise mode of action of this gram staining method is not understood well till now. But there are some theories that are useful to understand the gram reaction.

    One of the theories is the gram positive bacterial cells have more acidic protoplasm when compare the gram negative cells and this may useful to primary stain more tightly.

    The next theory & this theory almost justify the gram’s reaction that is the peptidoglycan layer of gram positive cells are thicker than the gram negative cells & because of this gram positive cells retain the dye-iodine complex.The gram negative cells can’t retain the complex, because of the thin layer of peptidoglycan. The procedure, Application & other important points of gram staining will be discussed in our future articles.

Acid fast staining

    Acid fast staining was discovered by Paul Ehrlich. He has stain the tubercle bacilli with the aniline dye, the tubercle bacilli was developed the resistance against the acid. After that Ziehl & Neelsen modifies the method and stain the tubercle bacilli. This Ziehl & Neelsen’s method is used widely.

    The basic principle of acid fast staining is when the carbol fuchsin added on the smear it will solubilizes the lipoidal materials in the cell wall of mycobacterium. Heat doing a crucial in penetration of carbol fuchsin to the cell wall. By the help heat the carbol fuchsin penetrates into the cytoplasm through the cell wall & stains the cell. The stained cells appear as red colour.

    The procedure, application & further details about Acid fast stain will be discussed in our future articles.

    And these are all the Universally used staining techniques. I hope you guys know some interesting things from the article. If you any queries, please feel free ask & comment your thoughts in the comment section.


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