5.1: Introduction
- Page ID
- 123347
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In our laboratory, bacterial morphology (form and structure) may be examined in two ways:
- by observing living unstained organisms (wet mount), or
- by observing killed stained organisms.
- see greater contrast between the organism and the background,
- differentiate various morphological types (by shape, arrangement, gram reaction, etc.),
- observe certain structures (flagella, capsules, endospores, etc.).
Videos reviewing techniques used in this lab:
1. Heat fixation
The bacteria are heat fixed by holding the bottom of the slide against the opening of a microincinerator for 10 seconds. The heat coagulates the organisms' proteins causing the bacteria to stick to the slide.
2. Chemical fixation
An air-dried smear of the organism is covered with several drops of 95% methanol and allowed to sit for 2 minutes, after which the methanol is poured off and the slide is again allowed to air dry. Chemical fixation has been shown to be better at enabling bacteria to adhere to the slide while causing less damage and distortion to the bacteria.
Contributors and Attributions
Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS)