The Diversity of Prokaryotic Organisms

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The Diversity of Prokaryotic Organisms

• Anaerobic chemotrophs
• Anoxygenic phototrophs
• Oxygenic phototrophs
• Aerobic chemolithotrophs . . . .
• Chemoorganotrophs (esp. medically important
  ones!)

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Prokaryotes

• Specifically an anaerobic bacterium
• Still many anaerobic habitats (tightly packed
  soil, polluted lakes, human body)
• First-Ever Scientific Estimate Of Total Bacteria
  On Earth Shows Far Greater Numbers Than Ever
  Known Before 5 million trillion trillion --
  that's a 5 with 30 zeroes after it (Proceedings
  of the National Academy of Sciences, 1998)
• Bacteria inside all animals combined make up lt 1
  of the total amount. By far the greatest numbers
  are in the soil and oceans.

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Anaerobic Chemoorganotrophs Using Fermentation

• Energy production only by substrate level
  phosphorylation. Different fermentation end
  products (acids and gases) for different species
• Genus Clostridium - forms endospores
• normal flora of GI tract
• tetanus
• botulism
• gas gangrene

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Lactic Acid Bacteria

• Major fermentation product?
• Example genera
• Streptococcus normal throat flora and S.
  pyogenes etc.
• Enterococcus normal GI-tract flora
• Lactobacillus normal mouth and vagina flora
  food fermentation
• Most can grow in aerobic environment but they are
  obligate fermenters (hence O2 is of no value!) ?
  lack catalase (diagnostic use)

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Streptococcus pneumoniae, which causes millions
of cases of of pneumonia and other infections
every year in the United States, is rapidly
becoming resistant to penicillin. (PNI)
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Aerobic Chemoorganotrophs Obligate Aerobes

• Large variety of bacteria example genera
• Micrococcus soil, objects, normal skin flora.
  E.g. M. luteus
• Mycobacterium saprophytes and pathogens waxy
  coat acid fast, pleomorphic rods more
  resistant to disinfectants and normal drugsE.g
  M. tuberculosis and M. leprae
• Pseudomonas motile gram neg. rods ubiquitous
  in soil and water mostly harmless, P.
  aeruginosa is a opportunistic pathogen very
  resistant to disinfectants and antimicrobial
  drugs
• Thermus (Taq polymerase)

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Aerobic Chemoorganotrophs Facultative Anaerobes

• Corynebacterium in soil, water, and on plants
  gram pos. pleomorphic rods (club) normal
  throat flora, but also C. diphtheriae
• Enterobacteriaceae family enterics
  enterobacteria what does name tell you?
  includes 40 genera if motile peritrichous
  flagella
• Enterobacter
• Klebsiella
• Proteus
• E.coli
• Shighella
• Salmonella
• E.coli

Proteus
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Ecophysiology Thriving in Terrestrial
Environments

• Bacteria had to evolve mechanisms to survive dry
  spells
• Most efficient method endospore formation
  Bacillus and Clostridium species (Position of
  endospore is diagnostic)
• Streptomyces genus forms conidia at the end of
  hyphae (analogous to fungi, but they are
  prokaryotes and much smaller than fungi)
• Producers of antibiotics (streptomycin,
  tetracycline, erythromycin)
• S. somaliensis causes actinomycetoma

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Animals as Habitats

• From arid O2 rich surfaces to moist anaerobic
  recesses
• Skin
• Staphylococcus aureus
• Staphylococcus epidermidis (normal flora)
• Both are catalase positive (as opposed to
  Strept enterococcus

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Mucous Membrane

• Already discussed Streptococcus in resp. tract.
  - Lactobacillus in vagina Clostridium and
  enterics in GI tract
• Some other genera
• Bacteroides (30 of bacteria in human feces)
• Campylobacter and Helicobacter (microaerophiles)
• Haemophilus (many normal flora of resp. tract as
  well as H. influenza and H. ducreyi)
• Neisseria (normal flora as well as N. gonorrhea
  and N. meningitis)
• Mycoplasma no cell wall fried egg appearance
  of culture colonies M. pneumoniae
• Treponema and Borrelia Spriochetes hard to
  grow in culture

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Obligate Intracellular Parasites

• Cannot reproduce outside a host cell
• Rickettsia and Ehrlichia Transferred by blood -
  sucking arthropods
• R. rickettsii Rocky Mountain spotted fever
• R. prowazekii epidemic typhus
• E. chaffeensis Human ehrlichiosis
• Coxsiella - Can form a sporelike structure
• One species C. burnetii Q fever Zoonosis

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3. Chlamydia

• Person to person transmission
• Unique growth cycle
• Non-infectious reticulate body reproduces by
  binary fission
• Differentiate into infectious elementary body
• Chlamydia cell wall does not contain
  peptidoglycan but resembles gram neg.
• C. trachomatis, C. pneumoniae

The End