Microscopic examination
The analysis of minute organisms, cellular organization of any biological structure, and composition of body fluids with the help of a microscope is known as microscopic examination. The magnification of specimens or samples under study helps in attaining a clearer picture of it.
Gram Staining
Named after Hans Christian Gram, a Danish bacteriologist, Gram stain is one of the most powerful staining techniques within microbiology. This technique was introduced in 1882 to identify pneumonia-causing organisms. The Gram staining technique uses crystal violet or methylene blue as primary staining colors to distinguish gram-positive from gram-negative organisms. Under a microscope, the gram-positive organisms appear purple-brown, retaining the primary color. Gram-negative organisms appear pink or red as they do not acquire the color of the primary stain.
A. Microscopic Observation of Cells Wet Mounts, Gram stain and spore stain
1 Describe the microscopic morphology and behavior of each species observed with a wet mount (A. serpens and E. gracilis).
2 Describe the microscopic morphology of each sample observed with a Gram stain (S. aureus, P. aeruginosa, B. subtilis and dental plaque). Indicate the Gram reaction of each.
3Describe the microscopic morphology of each sample observed with the spore stain (P. aeruginosa and B. subtilis). In which of the sample can you see spores?
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