Microbe of the Day Staphylococcus aureus

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Microbe of the DayStaphylococcus aureus
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Staphylococcus aureus

• Golden-colored colonies

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Staphylococcus aureus

• Behold Staphylococcus aureus,
• A gold-colored Gram positive coccus
• Staph lives on our skin
• And sometimes it gets in
• Making toxins that sure disagree with us!

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Staphylococcus aureus

• Gram positive coccus
• Grape-like clusters
• Common on skin and nose grows in high salt

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Staphylococcus aureus

• Opportunistic pathogen makes toxins
• Skin abscesses
• Food poisoning
• Toxic shock syndrome

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Staphylococcus aureus
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Staphylococcus aureus
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Prokaryotes

• Functional Anatomy
• Part 2

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TOPICS

• External structures
• Cell Envelope
• Internal Structures
• Cell Shapes, Arrangement, and Sizes
• Classification
• Archaea

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http//www.arches.uga.edu/kristenc/cellwall.html
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Gram Stain
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Gram Positive Bacteria
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Gram Negative Bacteria
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Atypical Cell Walls

• Mycobacteria (TB, leprosy)
• Very thick outer lipid layer - acid fast
• Slow nutrient exchange
• Slow growth

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Acid Fast StainMycobacteria
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Internal Structures

• Cytoplasm
• Genetic structures
• Storage bodies
• Actin
• Endospore

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Cytoplasm

• Site for cells biochemical activities
• 70-80 water
• Bacterial chromosome
• Ribosomes - protein synthesis
• Actin - cytoskeleton

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DNA - Bacterial Chromosome

• Single long circular chromosome
• Double-stranded DNA
• No nuclear envelope
• Attached to plasma membrane
• May have small circular DNA plasmids outside
  chromosome

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RNA

• Messenger RNA (mRNA) - transcribed from DNA,
  carries code for protein synthesis
• Transfer RNA (tRNA) - one for each amino acid
• Ribosomal RNA (rRNA) - structural part of ribosome

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Ribosome

• rRNA protein
• Site of protein synthesis
• Inhibited by some antibiotics

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Inclusion bodies

• Reserve deposits
• Nutrients
• minerals
• enzymes for CO2 fixation
• Magnetosomes (Fe3O4)
• Gas Vacuoles buoyancy

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Actin Cytoskeleton

• Found in rod-shaped and spiral bacteria just
  under plasma membrane
• Influences cell shape

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Endospores

• Highly durable dehydrated dormant cells (boil for
  20 hours to destroy)
• Allow cells to survive adverse conditions
• Sporulation is spore formation
• Germination is return to vegetative (growing) cell

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Spore Stain
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Medical Significance of Endospores

• Bacillus anthracis - anthrax
• bioterrorism
• Clostridium
• C. tetani - tetanus
• C. botulinum - botulism
• C. perfringens - gas gangrene

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Shapes and Arrangements of Bacterial Cells

• Coccus (cocci) spherical
• Bacillus (bacilli) rod-shaped
• Spirillum or Spirochete spiral
• Diplo - 2
• Tetrads - 4
• Strep - chains
• Staphylo - bunches

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Bacterial Cell Size

• 0.2-2 mm in diameter, 2-8 mm long
• Some bacteria have varied shapes (pleomorphism)
• Cellular shapes and arrangements can be used to
  identify bacteria

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Streptococcus pyogenes
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Streptococcus pneumoniae
diplococcus
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Escherichia coli and Bacillus subtilis
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Vibrio cholerae
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Borrelia burgdorferi
Leptospira interrogans
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Classification of Bacteria

• Phenotypic methods
• morphology (size, shape, colony morphology)
• growth characteristics
• Molecular methods
• genes, RNA
• antigens (immunology)
• Taxonomic Scheme
• Bergeys Manual of Determinative Bacteriology

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Medically Important Gram Positive Bacteria
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Medically Important Gram Negative Bacteria
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Unusual Bacteria

• Obligate intracellular parasites
• Lack some enzymes that they need for survival
• Rickettsias - Rocky Mtn Spotted Fever
• Chlamydias - blindness and STD

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Unusual Bacteria

• Photosynthetic Bacteria
• Cyanobacteria - blue-green bacteria

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Purple Sulfur Bacteria
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Unusual Bacteria

• Gliding, Fruiting Bacteria - Myxobacteria
• Gram negative bacteria
• Complex life cycle

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Archaea

• Prokaryotic
• Singluar circular chromosome
• Unique rRNA sequences
• Unique Cell membrane lipids
• No peptidoglyc an in cell walls
• Often live under extreme environmental conditions

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Archaea