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Classification of Bacteria. Taxonomy. The science of classification. Haeckel’s 3 Kingdoms. Plant Animal Protista. Carl Woese’s 3 Domains. Based on rRNA nucleotide sequences Why use this as a basis for classification?. Organisms in the 3 Domains.

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taxonomy

Taxonomy

The science of classification

haeckel s 3 kingdoms
Haeckel’s 3 Kingdoms
  • Plant
  • Animal
  • Protista
carl woese s 3 domains
Carl Woese’s 3 Domains

Based on rRNA nucleotide sequencesWhy use this as a basis for classification?

organisms in the 3 domains
Organisms in the 3 Domains
  • Eukarya - kingdoms: plantae, animalia, fungi, protists
  • Archaea - prokaryotes
  • Bacteria - prokaryotes
2 types of prokaryotic cells
2 Types of Prokaryotic Cells
  • Eubacteria
    • cell walls contain peptidoglycan
    • different nucleotide sequences in rRNA
    • different membrane lipids
  • Archaebacteria
    • no peptidoglycan
    • rRNA
    • lipids
    • live in extreme environments

ex. Thermoacidophiles

Extreme halophiles

Methanogens

http://www.ucmp.berkeley.edu/archaea/archaea.html

naming organisms nomenclature
Naming organisms (nomenclature)

Binomial system uses 2 names

Genusspecies

ex. Bacillus subtilis

ex. Clostridium tetani

ex. Staphylococcus aureus

Is tubercle bacillus the scientific name of an organism or a common name?

3 phylogenetic classification
3. Phylogenetic Classification
  • An evolutionary arrangement of species.
  • Sharing a recent ancestor as in plants and animals (fossil records)
  • In bacteria?
  • Possible by Molecular Methods
    • Genetic Homology:
      • Base composition (GC ratio)
      • Nucleic acid hybridisation.
      • Ribosomal RNA (rRNA) sequence analysis
      • Protein profiles and amino acid sequences
slide11
PURE CULTURE:
  • Populations of individuals all derived from the same single organism.
  • STRAIN:
  • A Group of Pure Cultures Derived from a Common Source and Thought to be the Same.
  • SPECIES:
  • A Group of Closely Similar Strains.
intraspecies classification
INTRASPECIES CLASSIFICATION
  • Biotypes
    • Biochemical properties.
  • Serotypes
    • Antigenic features.
  • Phage Types
    • Bacteriophage susceptibility.
  • Colicin Types
    • Production of bacteriocins.
slide13

Species of bacteria - “population of cells with similar characteristics”

Strain of bacteria - “group of cells derived from a single cell”

ex. Staphylococcus aureus 13578

slide14
Naming of microorganisms.
  • Governed by international rules
  • Rules published in the International Code of Nomenclature of Bacteria.
  • The International Journal of Systematic Bacteriology
rules for the nomenclature of microorganisms
Rules for the Nomenclature of Microorganisms
  • There is only one correct name for an organism.
  • Names that cause error or confusion should be rejected.
  • All names in Latin or are latinized.
    • The first word (genus) is always capitalized.
    • The second word (species or specific epithet) is not capitalized.
    • Both genus and species name, together referred to as species, are either underlined or italicized when appearing in print.
    • The correct name of a species or higher taxonomic designations is determined by valid publication, legitimacy of the name with regard to the rules of nomenclature, and priority of publication.
nomenclature
Nomenclature
  • Casual or Common Name:
  • e.g. "typhoid bacillus"
  • Scientific or International Name:
  • Salmonella typhi
  • Salmonella london
  • Staphylococcus aureus
  • Clostridium tetani
  • Mycobacterium bovis
  • Borrelia burgdorferi
classification vs identification techniques
Classification vs. Identification Techniques
  • Bergey’s Manual of Determinative Bacteriology uses:
  • microscopic appearance
  • biochemical reactions
  • growth requirements
  • serology
  • phage typing
  • Classification or identification??
serology
Serology

Slide Agglutination Test

bergey s manual of systematic bacteriology establishes phylogenetic relationships by
Bergey’s Manual of Systematic Bacteriology establishes phylogenetic relationships by:
  • amino acid sequencing
  • protein analysis
  • rRNA sequencing – ribotyping
    • Why is rRNA rather than other types of RNA used?
      • Chapter 10
  • nucleic acid hybridization

Classification or identification??

spirochetes
Spirochetes

Axial filaments for motility

Examples:

Treponema pallidum - syphillis

Borrelia burgdorferi - Lyme disease

Leptospira interrogans - leptospirosis

axial filaments
Axial Filaments

Movement of spirochetes

Structure

Filament

Hook

Basal body

Ex. Treponema pallidum

Bundles of fibrils that arise at the end of the cell beneath the outer sheath & spiral around the cell

campylobacter jejuni
Campylobacterjejuni
  • microaerophilic
  • motile vibrio
  • Gram negative
  • animals esp poultry & cattle
  • grows @ 42oC
  • most commonly identified bacterial cause of diarrhea in world (CDC)
    • unpasteurized milk
    • food
pseudomonas aeruginosa
Pseudomonasaeruginosa
  • Gram negative aerobic rod
  • “bacillus of blue-green pus”
    • pyocyanin pigment
  • fermented grape smell
  • normal flora
    • skin & intestine
  • unusual carbon sources
  • antibiotic resistant
  • infections
    • wound, ear, urinary, respiratory, burns
gram negative aerobic cocci
Gram negative aerobic cocci

Neisseria meningitidis

Branhamella catarrhalis

Neisseria gonorrhoeae in pus

enterobacteriales
Enterobacteriales

Family- enterobacteriaceae

Non-pathogens

  • Escherichia
  • Klebsiella
  • Proteus
  • Serratia
  • Etc.

Describe the microscopic appearance of these organisms.

enterobacteriaceae cont d
Enterobacteriaceae cont’d

Pathogens

  • Salmonella (typhi)
    • typhoid fever
  • Shigella (dysenteriae)
    • bacillary dysentery
  • Yersinia (pestis)
    • bubonic plague

All members of Enterobacteriaceae are facultative anaerobes. Meaning?

Can you see why the family, enterobacteriaceae, has been referred to as the Colon-typhoid-dysentery group?

Can you differentiate the pathogens from the non-pathogens microscopically?

vibrionales

Vibrionales

Shape?

Facultatively anaerobic

Vibrionaceae

Vibriocholerae

hemophilus influenzae
Hemophilusinfluenzae
  • Aerobic Gram negative rod
  • Normal flora in intestine and respiratory tract
  • Most common cause of meningitis in children
    • Hib vaccine
  • Also causes otitis media, pneumonia, epiglottitis

Why is the name of this organism misleading?

What can you learn from the name?

bacteroidaceae bacteroides fragilis
Bacteroidaceae - Bacteroides fragilis
  • Gram negative anaerobic rods
  • Found in the human intestine & mouth
    • 95% of the bacteria in a stool specimen & 20% of the weight!
    • One billion per gram of feces!
  • Most common anaerobe isolated from infections
    • appendicitis, peritonitis, complicate abdominal surgery
rickettsia chlamydia gram negative obligate intracellular parasites

Rickettsia & ChlamydiaGram negative obligate intracellular parasites

Rickettsia

transmitted to humans by insects & ticks

Ex. Rickettsia rickettsii - Rocky Mountain spotted fever

chlamydia
Chlamydia

Not transmitted by insects

Causes:

1.Trachoma - world’s leading infectious cause of blindnessMiddle East, North Africa, India

Chlamydia trachomatis

2.Non-gonococcal urethritis common std in U.S.

slide36

Chlamydia psittacicauses:

1. Psittacosis (“parrot fever”)

2. Ornithosis

Chlamydia pneumoniae - pneumonia

mycoplasmas
Mycoplasmas
  • No cell wall
    • pleomorphic
    • penicillin sensitive or resistant?
  • Smallest free-living organisms
  • Microscopic fried-egg colonies
  • Ex. Mycoplasma pneumoniae
gram positive cocci
Gram Positive Cocci

Staphylococcus

Streptococcus

Micrococcusluteus

staphylococcus aureus
Staphylococcusaureus
  • Gram positive cocci, clusters
  • Yellow pigment
  • Causes
    • common food poisoning
    • surgical wound infections
      • resistance
    • toxic shock syndrome
streptococcus pyogenes
Streptococcuspyogenes
  • Gram positive cocci in chains
  • Diseases
    • pharyngitis (sore throat)
    • scarlet fever *
    • erysipelas *

* look for a description of this disease

endospore forming gram positive rods
Endospore-Forming Gram Positive Rods
  • Bacillales - Bacillus
    • aerobes or facultative anaerobes
    • common in soil
    • ex. Bacillus anthracis, Bacillus subtilis
  • Clostridiales - Clostridium
    • obligate anaerobes
    • found in soil
    • diseases
      • tetanus (Clostridium tetani), botulism (C. botulinum),gas gangrene (C. perfringens)
spore forming organisms
Spore-Forming Organisms

Clostridium tetani - Gram stain

Bacillus cereus - spore stain

corynebacterium
Corynebacterium

Characteristics of Corynebacterium sp.:

  • pleomorphic Gram positive rod
  • metachromatic granules
  • unusual arrangements
    • palisades
    • Chinese letters
  • C.diphtheriae causes diphtheria
mycobacteria
Mycobacteria

Characteristics of Mycobacterium sp.

  • Gram positive small rods
  • acid-fast
    • mycolic acid complexed with peptidoglycan (waxy)
  • diseases:
    • tuberculosis
    • leprosy (M. leprae)

Acid-fast stain of sputum showing Mycobacterium tuberculosis

streptomycetes
Streptomycetes

Characteristics of Streptomyces:

  • mold-like bacteria
    • branching, spores
  • produce geosmin
    • soil smell
  • several species produce antibiotics
    • ex. streptomycin