Prokaryotic MicrobesProkaryotic Microbes
Domain BacteriaDomain Bacteria
Yersinia pestis – Bubonic Plague. science.nationalgeographic.com Clostridium botulism.
www.nih.gov
Classifying BacteriaClassifying Bacteria
Bergey’s Manual of Systematic Bacteriology
A bacteriologist’s “bible”.
5 volumes.
www.buy.com
3 Phenotypic Categories3 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.
Other Characteristics Used to Other Characteristics Used to Classify BacteriaClassify Bacteria
Cell morphology Staining reactions Motility Colony morphology Atmospheric requirements Nutritional requirements Biochemical and metabolic activities Specific enzymes produced Pathogenicity Genetic composition
Cell MorphologyCell Morphology
3 Basic Shapes of Bacteria– 1. Cocci
Round or spherical bacteria
– 2. Bacilli Rectangular or rod-
shaped bacteria
– 3. Spirilla Curved or spiral-
shaped bacteria
www.foodsafety.gov
CocciCocciDiplococci
– pairs
Streptococci– chains
Staphylococci– clusters
Tetrads– Packets of four
Octads (sarcina)– Packets of eight
Examples of Cocci BacteriaExamples of Cocci Bacteria
Neisseria gonorrhoeae – causes gonorrhea. Red diplococci cells. www.nature.com
Streptococcus pyogenes – strep throat. Streptococci – cocci in chains. bioweb.uwlax.edu
Staphylococcus aureus – Boils. Staphylococci – cocci in clusters. science.uniserve.edu.au
BacilliBacilli Come in many variations
of rod-shaped cells. Diplobacilli
– pairs
Streptobacilli– chains
Coccobacilli – Short, elongated-looking
cocci
Palisade arrangement– Side by side arrangement
Examples of Bacilli-shaped BacteriaExamples of Bacilli-shaped Bacteria
Haemophilus influenzae. Strain that causes a type of influenza. www.sanofipasteur.us
Escherichia coli. www.lbl.gov
Bacillus anthracis. www.lbl.gov
Spirilla – Curved and Spiral Spirilla – Curved and Spiral Shaped BacteriaShaped 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.
Spiral Shaped BacteriaSpiral Shaped Bacteria
Vibrio cholerae – cause of cholera. Vibrio. microbewiki.kenyon.edu
Campylobacter spp. Causes diarrhea. Spirilla. www.campylobacterblog.com
Treponema pallidum – cause of syphilis. Cell attached to testicular cell membranes. Spirochete. www.britannica.com
Borrelia burgdorferi – cause of Lyme disease. Spirochete. cellbiology.med.unsw.edu.au
Staining ProceduresStaining Procedures
Prior to staining bacteria must be:– 1. Smeared on glass slide.– 2. Air-dried.– 3. Fixed on slide by heat or methanol.
Heat fixing organism. biology.clc.uc.edu
Smearing bacteria on slide. www.cvgs.k12.va.us
2 Types of Fixation2 Types of Fixation
1. Heat Fixation– Run slide over a Bunsen burner.
2. Methanol Fixation– Flood slide with methanol for 30 seconds.
Staining BacteriaStaining 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.
Differential Staining ProcedureDifferential Staining Procedure
Process that allows differentiation of one group of bacteria from another.
2 common procedures:– Gram Stain– Acid-fast Staining Procedure
Gram StainGram Stain
Dr. Hans Christian Gram (1883) developed the gram stain.
Differentiates gram-positive bacteria from gram-negative bacteria.
www.scielo.org.ve
Bacterial Cell WallBacterial Cell Wall
Gram-positive 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-positive Bacteria
Gram-negative Bacteria
pathmicro.med.sc.edu
Gram Stain Procedure – Step 1Gram Stain Procedure – Step 1
www.cvgs.k12.va.us
Gram Stain Procedure – Step 2Gram Stain Procedure – Step 2
biology.clc.uc.edu
Gram Staining Procedure – Step 3Gram Staining Procedure – Step 3
z.about.com
Gram Staining Procedure – Step 4Gram Staining Procedure – Step 4
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Gram Staining Procedure – Step 5Gram Staining Procedure – Step 5
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Gram Staining Procedure – Step 6Gram Staining Procedure – Step 6
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Gram Staining Procedure – Step 7Gram Staining Procedure – Step 7
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Gram Staining Procedure – Step 8Gram Staining Procedure – Step 8
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Gram Staining Procedure – Step 9Gram Staining Procedure – Step 9
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Gram Staining Procedure – Step 9Gram Staining Procedure – Step 9
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Gram Staining Procedure – Step 10Gram Staining Procedure – Step 10
www.slic2.wsu.edu
www.carolina.com
Gram Stain ResultsGram Stain Results
Gram-positive bacteria stains violet to blue.
Gram-negative bacteria stains pink to red.
homepage.ntlworld.com
Bacterial Cell WallBacterial Cell Wall
www.biologie.uni-hamburg.de
Mycobacterium Mycobacterium SpeciesSpecies
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. www.kaiscience.com
Bacterial MotilityBacterial Motility
Axial filaments– 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.
Axial FilamentsAxial Filaments
http://classes.midlandstech.com/carterp/Courses/bio225/chap04/lecture3.htm
Flagella ArrangementsFlagella 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.
Flagella ArrangementsFlagella 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 Flagellastudent.ccbcmd.edu/courses/bio141/lecguide/unit1/
prostruct/flag.html
Other Methods for Other Methods for Determining MotilityDetermining Motility
Tube of semisoft motility medium
Hanging-drop technique
Deep tube of semisoft motility medium. Left = positive for motility. Right = negative for motility. www.alpena.cc.mi.us
Colony MorphologyColony Morphology
Appearance of bacterial colonies– Size, color,
overall shape, elevation, appearance of the edge of the colony
www.foodmate.net
Atmospheric RequirementsAtmospheric 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.
Nutritional RequirementsNutritional 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).
Biochemical and Metabolic Biochemical and Metabolic ActivitiesActivities
All bacteria produce specific metabolic byproducts, which may be specific enzymes or gases.
These are additional clues in determining the identity of certain bacteria.
PathogenicityPathogenicity
Does a bacteria produce a certain disease?
Genetic CompositionGenetic 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.
We will look at specific types of We will look at specific types of bacteria when we get to the bacteria when we get to the
disease reports disease reports
Domain ArchaeaDomain 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.
Domain ArchaeaDomain Archaea
www.nsf.gov
The End The End