The microscope is a very important tool to observe and identify microorganisms. A distinction must be made between the techniques used to observe live microorganisms and the preparations for staining. Staining provides additional information to the simple observation of the morphology, seeing as it highlights characteristics of the cell wall or the existence of special structures, such as the bacterial spores.

To observe bacteria under the microscope the oil immersion objective is used (maximum magnification). This involves putting a drop of immersion oil on the preparation. To focus with this objective, put the preparation with the oil on the slide of the microscope, bring it closer with the macrometric screw LOOKING FROM OUTSIDE, until the objective touches the oil.

Then, now looking through the eyepiece, focus roughly with the help of this screw. When an image becomes more or less clear, adjust the focus with the macrometric screw.

• Direct observation
• Heat fixation
• Gram staining
• Spore staining
• Ziehl-Neelsen staining
• Staining for fungi
• Observation of parasites

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