Page 42 - MNUmicrobiology practical 2025
P. 42
General Microbiology & Immunology (PM 401) second level Semester 4 2024/2025
Learning outcomes
• Prepare a good bacterial smear
• Illustrate the steps of simple stain
• Discuss the mechanism of simple staining of bacteria
• Use the microscope to identify bacterial features (cell shape and cell
arrangements).
Preparation of bacterial smear
Overview
A bacterial smear is a thin layer of bacterial cell/culture which is placed on a clean,
grease-free microscopic slide to observe a clear image under a microscope.
Bacterial smear purpose
The main purpose of bacterial smear preparation is to fix the bacterial cell on the
slide and prevent the loss of bacterial cells during the staining procedure.
Bacterial smear preparation principle
• Bacterial smear preparation involves the spreading of bacterial culture on slide,
air or heat drying, heat fixing before staining and microscopic observation.
• The heat fixing in smear preparation has a purpose, it kills the bacterial cells in
the smear, tightly adheres the smear to the slide, and allows the sample to more
easily take up stains.
General Microbiology & Immunology (PM 401) Practical note Page 31
