1. Prokaryotic Microbes

2. Domain Bacteria
Yersinia pestis – Bubonic Plague. science.nationalgeographic.com
Clostridium botulism.

3. Classifying Bacteria Bergey’s Manual of Systematic Bacteriology
A bacteriologist’s “bible”.
5 volumes.

4. 3 Phenotypic Categories
1. Bacteria that are gram-negative with a cell wall.
2. Bacteria that are gram-positive with a cell wall.
3. Bacteria that do not possess a cell wall.

5. Other Characteristics Used to Classify Bacteria
Cell morphology
Staining reactions
Motility
Colony morphology
Atmospheric requirements
Nutritional requirements
Biochemical and metabolic activities
Specific enzymes produced
Pathogenicity
Genetic composition

6. Cell Morphology 3 Basic Shapes of Bacteria 1. Cocci 2. Bacilli
Round or spherical bacteria
2. Bacilli
Rectangular or rod-shaped bacteria
3. Spirilla
Curved or spiral-shaped bacteria

7. Cocci Diplococci Streptococci Staphylococci Tetrads Octads (sarcina)
pairs
Streptococci
chains
Staphylococci
clusters
Tetrads
Packets of four
Octads (sarcina)
Packets of eight

8. Examples of Cocci Bacteria
Staphylococcus aureus – Boils. Staphylococci – cocci in clusters. science.uniserve.edu.au
Streptococcus pyogenes – strep throat. Streptococci – cocci in chains. bioweb.uwlax.edu
Neisseria gonorrhoeae – causes gonorrhea. Red diplococci cells.

9. Bacilli Come in many variations of rod-shaped cells. Diplobacilli
pairs
Streptobacilli
chains
Coccobacilli
Short, elongated-looking cocci
Palisade arrangement
Side by side arrangement

10. Examples of Bacilli-shaped Bacteria
Escherichia coli.
Haemophilus influenzae. Strain that causes a type of influenza.
Bacillus anthracis.

11. Spirilla – Curved and Spiral Shaped Bacteria
Vibrio
Comma shaped (incomplete spirals).
Spirillum
Large spiral shaped bacteria that have flagella for locomotion.
Spirochete
Slender spiral shaped bacteria that have axial filaments for locomotion.

12. Spiral Shaped Bacteria
Vibrio cholerae – cause of cholera. Vibrio. microbewiki.kenyon.edu
Treponema pallidum – cause of syphilis. Cell attached to testicular cell membranes. Spirochete.
Campylobacter spp. Causes diarrhea. Spirilla.
Borrelia burgdorferi – cause of Lyme disease. Spirochete. cellbiology.med.unsw.edu.au

13. Staining Procedures Prior to staining bacteria must be:
Smearing bacteria on slide.
Heat fixing organism. biology.clc.uc.edu
Prior to staining bacteria must be:
1. Smeared on glass slide.
2. Air-dried.
3. Fixed on slide by heat or methanol.

14. 2 Types of Fixation 1. Heat Fixation 2. Methanol Fixation
Run slide over a Bunsen burner.
2. Methanol Fixation
Flood slide with methanol for 30 seconds.

15. Staining Bacteria Used to observe bacterial cell morphology.
Size, shape, morphologic arrangement, cell wall composition, capsules, flagella, and endospores
Simple Stain
Using only one stain.
Enables viewer to determine bacterial shape and morphologic arrangement.
Example – staining with methylene blue.

16. Differential Staining Procedure
Process that allows differentiation of one group of bacteria from another.
2 common procedures:
Gram Stain
Acid-fast Staining Procedure

17. Gram Stain Dr. Hans Christian Gram (1883) developed the gram stain.
Differentiates gram-positive bacteria from gram-negative bacteria.

18. Bacterial Cell Wall Gram-positive Bacteria Gram-negative Bacteria
Thick layer of peptidoglycan (60-100%)
Contains teichoic acid and lipoteichoic acids (0-40%)
Gram-negative Bacteria
Thin layer of peptidoglycan (10-20%)
Has outer membrane composed of mostly lipids (80-90%)
Gram-negative Bacteria
pathmicro.med.sc.edu

19. Gram Stain Procedure – Step 1

20. Gram Stain Procedure – Step 2
biology.clc.uc.edu

21. Gram Staining Procedure – Step 3
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22. Gram Staining Procedure – Step 4
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23. Gram Staining Procedure – Step 5
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24. Gram Staining Procedure – Step 6
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25. Gram Staining Procedure – Step 7
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26. Gram Staining Procedure – Step 8
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27. Gram Staining Procedure – Step 9
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28. Gram Staining Procedure – Step 9
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29. Gram Staining Procedure – Step 10

30. Gram Stain Results Gram-positive bacteria stains violet to blue.
Gram-negative bacteria stains pink to red.
homepage.ntlworld.com

31. Bacterial Cell Wall

32. Mycobacterium Species
Gram-variable bacteria.
Is technically considered a gram-positive bacteria.
Does not stain well with crystal violet because its cell wall contains wax which prevents stains from entering cells.
Use Acid-Stain Procedure to stain this type of bacteria.
Mycobacterium tuberculosis – causes tuberculosis.

33. Bacterial Motility Axial filaments Gliding motility Flagella
Internal flagella found only in spirochete bacteria.
Found between outer membrane and cell wall.
Gliding motility
Encapsulated bacteria (e.g. slime capsule).
Flagella
Can have different arrangements.
Use different stains to identify certain number, arrangement, and location of flagella.

34. Axial Filaments

35. Flagella Arrangements
Monotrichous flagellation
Single flagellum.
Amphitrichous flagellation
Single flagellum at each end of the cell.
Lophotrichous flagellation
Tuft (2 or more) flagella at one or both poles of the cell.
Peritrichous flagellation
Flagella covering the entire cell surface.

36. Flagella Arrangements
Monotrichous Flagellum of Vibrio cholerae
Spirillum with Amphitrichous Arrangement of Flagella
Spirillum with Lophotrichous Arrangement of Flagella
Flagella Stain of Proteus Showing Peritrichous Arrangement of Flagella
student.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/flag.html

37. Other Methods for Determining Motility
Tube of semisoft motility medium
Hanging-drop technique
Deep tube of semisoft motility medium. Left = positive for motility. Right = negative for motility.

38. Colony Morphology Appearance of bacterial colonies
Size, color, overall shape, elevation, appearance of the edge of the colony

39. Atmospheric Requirements
Obligate aerobes
Need oxygen (O2) concentrations comparable to room air.
Microaerophilic aerobes
Need O2 but less concentration.
Facultative anaerobes
Can grow in the presence of either O2 or carbon dioxide (CO2)
Aerotolerant anaerobes
Does not need O2, grows better in its absence, can survive in presence of O2.
Obligate anaerobes
Can only grow in the absence of O2.

40. Nutritional Requirements
All bacteria need some form of the elements:
carbon, hydrogen, oxygen, sulfur, phosphorus, and nitrogen to grow.
Depending on the species, there may be additional nutritional requirements (i.e. copper, zinc, calcium, iron to name a few).

41. Biochemical and Metabolic Activities
All bacteria produce specific metabolic byproducts, which may be specific enzymes or gases.
These are additional clues in determining the identity of certain bacteria.

42. Pathogenicity
Does a bacteria produce a certain disease?

43. Genetic Composition Every species has unique genetic material.
Molecular diagnostic procedures can be used to identify an organism’s specific genetic material.
This may be RNA or DNA.

44. We will look at specific types of bacteria when we get to the disease reports 

45. Domain Archaea
Thought to have diverged from bacteria soon after life appeared.
Archaea share more genes with eukaryotes.
Therefore, thought that archaea and eukarya diverged early in life history.
Many but not all are extremophiles.
Have a cell wall but don’t possess peptidoglycan.

46. Domain Archaea

47. The End