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Classification of Bacteria

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.

Gabriel
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Classification of Bacteria

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  1. Classification of Bacteria

  2. Taxonomy The science of classification

  3. Haeckel’s 3 Kingdoms • Plant • Animal • Protista

  4. Carl Woese’s 3 Domains Based on rRNA nucleotide sequencesWhy use this as a basis for classification?

  5. Organisms in the 3 Domains • Eukarya - kingdoms: plantae, animalia, fungi, protists • Archaea - prokaryotes • Bacteria - prokaryotes

  6. 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

  7. Comparison of Archaea, Bacteria & Eukarya

  8. 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?

  9. Taxonomic Categories Order ends in –ales in fungi, plantae & bacteria Family ends in- aceae infungi, plantae & bacteria

  10. Species of bacteria - “population of cells with similar characteristics” Strain of bacteria - “group of cells derived from a single cell” ex. Staphylococcus aureus 13578

  11. Classification vs. Identification Techniques • Bergey’s Manual of Determinative Bacteriology uses: • microscopic appearance • biochemical reactions • growth requirements • serology • phage typing • Classification or identification??

  12. Biochemical Tests

  13. Serology Slide Agglutination Test

  14. Phage Typing

  15. 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??

  16. DNA Hybridization

  17. Identification vs. Classification

  18. Spirochetes Axial filaments for motility Examples: Treponema pallidum - syphillis Borrelia burgdorferi - Lyme disease Leptospira interrogans - leptospirosis

  19. 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

  20. 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

  21. 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

  22. Gram negative aerobic cocci Neisseria meningitidis Branhamella catarrhalis Neisseria gonorrhoeae in pus

  23. Enterobacteriales Family- enterobacteriaceae Non-pathogens • Escherichia • Klebsiella • Proteus • Serratia • Etc. Describe the microscopic appearance of these organisms.

  24. 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?

  25. Vibrionales Shape? Facultatively anaerobic Vibrionaceae Vibriocholerae

  26. 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?

  27. 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

  28. Rickettsia & ChlamydiaGram negative obligate intracellular parasites Rickettsia transmitted to humans by insects & ticks Ex. Rickettsia rickettsii - Rocky Mountain spotted fever

  29. 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.

  30. Chlamydia psittacicauses: 1. Psittacosis (“parrot fever”) 2. Ornithosis Chlamydia pneumoniae - pneumonia

  31. Mycoplasmas • No cell wall • pleomorphic • penicillin sensitive or resistant? • Smallest free-living organisms • Microscopic fried-egg colonies • Ex. Mycoplasma pneumoniae

  32. Gram Positive Cocci Staphylococcus Streptococcus Micrococcusluteus

  33. Staphylococcusaureus • Gram positive cocci, clusters • Yellow pigment • Causes • common food poisoning • surgical wound infections • resistance • toxic shock syndrome

  34. Streptococcuspyogenes • Gram positive cocci in chains • Diseases • pharyngitis (sore throat) • scarlet fever * • erysipelas * * look for a description of this disease

  35. 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)

  36. Spore-Forming Organisms Clostridium tetani - Gram stain Bacillus cereus - spore stain

  37. Corynebacterium Characteristics of Corynebacterium sp.: • pleomorphic Gram positive rod • metachromatic granules • unusual arrangements • palisades • Chinese letters • C.diphtheriae causes diphtheria

  38. 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

  39. Streptomycetes Characteristics of Streptomyces: • mold-like bacteria • branching, spores • produce geosmin • soil smell • several species produce antibiotics • ex. streptomycin

  40. The End!

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