Archaebacteria, Mycobacteria, Mycoplasmas

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Archaebacteria, Mycobacteria, Mycoplasmas
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Archaebacteria

• There are four types of cell wall for the
  archaebacteria
• 1. Pseudopeptidoglycan, found in some methanogens
• 2. A thick layer of polysaccharides
• 3. Glycoprotein
• 4. Surface layer proteins

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• Similarities to bacteria
• DNA is mostly circular
• They are prokaryotic
• 70s ribosomes

• Similarities to eukaryotes
• They have histones
• Cell wall doesnt have muramic acid
• Initiator tRNA is methionine

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Archaea Extremophiles

• Methanogens
• Anaerobic
• Can be found in mud at bottoms of lakes and
  swamps, the intestinal tract of humans and some
  animals
• Most can grow on CO2 and H2 as their source of
  energy.
• Halophiles
• Can be found in places with high salt
  concentration
• Most are photosynthetic autotrophs
• Thermoacidophiles
• Thrive in conditions with high temperatures and
  high acid concentration
• Many are chemoautotrophs
• Have extremozymes
• Flagella make them motile.

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Thermophiles
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Importance

• Currently, there not any known archaean
  pathogens.
• Ecologically, methanogens remove excess amounts
  of hydrogen and fermentation products that have
  been reproduced by anaerobic respiration.
• Thermophiles contain enzymes that are used in DNA
  fingerprinting.

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Mycobacteria

• Mycobacterium leprae with human endothelial cells
• A is at 3 hours
• B is at 6 hours
• C is at 24 hours

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Mycobacteria cell wall

• The cell wall is waxy, hydrophobic and has high
  lipid content
• Up to 60 of the dry weight of the organisms may
  be mycolic acids- long chain, branched fatty
  acids
• The type of mycolic acid can be used to
  distinguish different mycobacteria
• The mycolic acids and short chain fatty acids
  form a pseudo outer membrane and are responsible
  for the unusual staining characteristics of the
  cells
• The wall is also responsible for the
  hydrophobicity of these organisms
• The wall has adjuvant properties and may be
  responsible for the development of delayed type
  hypersensitivity (DTH)
• All mycobacterial pathogens are intracellular
  pathogens- the wall helps the organism to survive
  within the macrophage by resisting oxidative
  damage

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Mycobacteria

• Most Mycobacteria are bacilli
• The standard gram stain doesnt work because of
  their waxy coat
• When they shed their cell wall they are known as
  Spheroplasts
• They are nonmotile
• They are classified by their development of
  pigments
• They are gram-positive aerobes or facultative
  anaerobes

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Importances

• Mycobacterium leprae causes leprosy
• Each year about 600,000 people are diagnosed with
  leprosy.
• Predominantly found in South-East Asia
• Causes skin lesions and sensory loss
• Mycobacterium tuberculosis
• Main site of infection is in the lungs and is
  chronic
• Other mycobacterium organisms are responsible for
  opportunistic infections

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Mycoplasmas

• Do not have a cell wall
• Can take on many different shapes
• When they attach to a host cell they generate and
  release Hydrogen Peroxide

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Movement and Nutrition

• Have special organelles to help it attach to a
  host cell
• They are strictly parasites
• Have a very small genome and the minimum set of
  organelles

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Mycoplasma pneumoniae

• Symptoms
• Nonproductive cough
• Sore throat
• Middle-ear involvement
• Low fever
• The incubation period is about three weeks.

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Literature Cited

• http//www.encyclopedia.com/doc/1E1-Archaea.html
• http//paleontology.wikia.com/wiki/Three-domain_sy
  stem
• http//web.uct.ac.za/depts/mmi/lsteyn/cellwall.htm
  l
• http//web.uct.ac.za/depts/mmi/lsteyn/lecture.html
  
• http//microbewiki.kenyon.edu/index.php/Mycoplasma
  
• http//s99.middlebury.edu/BI330A/projects/Howard/M
  pneumoniae.html
• http//www.nature.com/labinvest/journal/v80/n5/fig
  _tab/3780069f2.html
• http//gsbs.utmb.edu/microbook/ch037.htm
• http//iai.asm.org/cgi/content/full/76/1/71/F1
• http//www.ucmp.berkeley.edu/archaea/archaea.html
• http//www.newworldencyclopedia.org/entry/Cell_wal
  l