LAB 7: ENDOSPORE STAIN AND BACTERIAL MOTILITY

 

A. ENDOSPORE STAIN

DISCUSSION

A few genera of bacteria, such as Bacillus and Clostridium have the ability to produce resistant survival forms termed endospores. Unlike the reproductive spores of fungi and plants, these endospores are resistant to heat, drying, radiation, and various chemical disinfectants (see Labs 19 and 20)

To view an electron micrograph of an endospore of Bacillus stearothermophilus, see the Microbe Zoo web page of Michigan State University.

Scanning electron micrograph of Clostridium botulinum with endospore; courtesy of Dennis Kunkel's Microscopy.

Scanning electron micrograph of Bacillus anthracis endospores; courtesy of CDC.

For more information on bacterial endospores, see Unit 1, Section B3e in your Lecture Guide.

2. Place a piece of blotting paper over the smear and saturate with malachite green (see Fig. 19).

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Bacterial motility constitutes unicellular behavior. In other words, motile bacteria are capable of a behavior called taxis. Taxis is a motile response to an environmental stimulus and functions to keep bacteria in an optimum environment.

 

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ORGANISMS

Trypticase Soy broth cultures of Pseudomonas aeruginosa and Staphylococcus aureus. Caution: handle these organisms as pathogens.

 

MEDIUM

Motility Test medium (2 tubes)

PROCEDURE (to be done individually and in pairs)

1. Observe the phase-contrast microscopy demonstration of motile Pseudomonas aeruginos.

Movie of motile Pseudomonas from YouTube.

2. Observe the dark-field microscopy demonstration of motile Pseudomonas aeruginosa.

3. Take 2 tubes of Motility Test medium per pair. Stab one with Pseudomonas aeruginosa and the other with Staphylococcus aureus. Stab the bacterium about 1/2 - 3/4 of an inch into the agar, taking care not to tilt or twist the loop so that the loop comes up through the same cut as it went down. Incubate the tubes in your test tube rack at 37°C until the next lab period.

4. Observe the flagella stain demonstrations of a Vibrio species (monotrichous), Proteus vulgaris (peritrichous) and Spirillum undula (amphitrichous) as well as the dark-field photomicrograph of the spirochete Leptospira. When observing flagella stain slides, keep in mind that flagella often break off during the staining procedure so you have to look carefully to observe the true flagellar arrangement.

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RESULTS

A. Endospore Stain

Make drawings of the various endospore stain preparations.

 

 


Endospore stain of Bacillus megaterium

 


Endospore stain of Bacillus anthracis


Endospore stain of Clostridium tetani

B. Bacterial Motility

1. Observe the phase contrast and dark-field microscopy demonstrations of bacterial motility.

2. Observe the two tubes of Motility Test medium.

Conclusion:


Conclusion:

 

 

3. Make drawings of the flagella stain demonstrations.



Flagella stain of a
Vibrio
species


Flagella stain of
Proteus vulgaris


Flagella stain of
Spirillum undula

Arrangement =

 

Arrangement =

 

Arrangement =

 

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PERFORMANCE OBJECTIVES FOR LAB 7

After completing this lab, the student will be able to perform the following objectives:

A. ENDOSPORE STAIN

DISCUSSION

1. Name two endospore-producing genera of bacteria.

2. State the function of bacterial endospores.

RESULTS

1. Recognize endospores as the "structures" observed in an endospore stain preparation.

2. Identify a bacterium as an endospore-containing Clostridium by its "tennis racquet" appearance.

B. BACTERIAL MOTILITY

DISCUSSION

1. Define the following flagellar arrangements: monotrichous, lophotrichous, amphitrichous, peritrichous, and axial filaments.

2. State the function of bacterial flagella.

3. Describe three methods of testing for bacterial motility and indicate how to interpret the results.

 

RESULTS

1. Recognize bacterial motility when using phase-contrast or dark-field microscopy.

2. Interpret the results of Motility Test Medium.

3. Recognize monotrichous, lophotrichous, amphitrichous, and peritrichous flagellar arrangements.

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SELF-QUIZ

Self-quiz

Answers

 

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Copyright © Gary E. Kaiser
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Updated: March, 2012
Please send comments and inquiries to Dr. Gary Kaiser