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Old Eubacteria

• Blessing Chirenje
• Alice Wagner

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Aquificae

• Oldest branch of Bacteria.
• One class, one order and fiver genera Aquifex
  and Hydrogenobacter.
• Oxidize hydrogen, thiosulfate, and sulfur O2
  electron acceptor.

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Aquificae

• Thermophilic associated mainly with hot springs,
  sulfur pools, thermal ocean vents.
• Chemolithotroph utilizes carbon dioxide as sole
  source of carbon energy from the oxidation of
  inorganic compounds.

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Aquificae

• Gram Negative Rod
• Form large cell aggregates, containing up to
  about 100 individuals.
• Genus Aquifex grows best at 85C and can grow at
  temperatures up to 95C.

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Aquifex aeolicus

• Genome 1/3 of E. coli reduced metabolic
  flexibility cannot grow on sugars, amino acids.
• 16 of coding sequences similar to archaeal genes.

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Thermotogae

• Thermophilic optimal growth 80-90C
• Found in geothermally heated soils and marine
  sediments.
• Gram Negative Rod
• Chemoorganotroph depends on organic chemicals
  for energy and carbon.

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Thermotogae

• Cell wrapped in sheathe-like outer membrane
  (toga).
• Anaerobic reduces cystine and thiosulfate to
  hydrogen sulfide.
• Metabolize carbohydrates glucose, sucrose,
  starch, cellulose
• Functional glycolytic pathway.

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Thermotoga
T. subterranea strain SL1 was found in a 70C
deep continental oil reservoir. T. Maritima
consists of one circular chromosome 1,860,725
bp. Varying amounts of salt and oxygen
tolerance. 81 Aracheal-like genes. 24 Nature
1999, 399 (6734)323-9
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Deinococcus-Thermus

• One class, two orders Deinococcales and
  Thermales
• Three phylum of which Deinococci is best studied
• Deinococci are spheres or rod-shapped with
  distinct 16s rRNA

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Deinococcus

• GPC or GPR  resistant to radiation, extreme
  heat, extreme cold, drying, vacuum of space.
• Breakdown nuclear waste and toxic chemicals.
• Isolated from ground meat, feces, air, fresh
  water.
• Natural habitat unknown.

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Deinococcus

• Aerobic, mesophilic heterotrophs occur in clouds
  and rainwater and which can spoil food.
• Highly resistant to gamma and X-rays
• Very efficient DNA repair system.
• D. radiodurans have 4-10 copies of their DNA
  molecule. Most bacteria have only one copy.
• Megaplasmid and small plasmid chromosomes

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Deinococcus

• Associated in pairs or tetrads
• Atypical GP cell wall periplasmic space has large
  amounts of palmitoleic acid.
• D. radiodurans radiation 1000X greater than
  would kill a human.
• Latin "strange berry that withstands radiation.

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Thermus thermophilus

• Thermophilic heterotrophs found in warm water
  environments especially hot springs.
• Source of Taq polymerase used in the PCR
• enables DNA to be replicated in large
  quantities. 

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Thermus thermophilus

• Gram-negative bacteria.
• Optimal growth temperature of 48C and 85C
• Ribosomes and ribosomal subunits do not
  disintegrate when kept for longer periods at
  20C'
• Down-temperature evolution
• Crystal structure of homoisocitrate dehydrogenase
  

1999, University of Wisconsin, Board of Regents.
'Cell 102 615-623 (2000)
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Chlamydia

• The phylum Chlamydiae has one class, one order,
  four families and six genera.
• They evloved about 2 billion years ago.
• Nonmotile, coccoid, gram-neagtive.
• One of the smallest of all bacteria 500 nm in
  width, not much bigger than the largest viruses.

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Chlamydia

• Obligate Intracellular bacteria with a unique
  developmental cycle involving elementary bodies
  (EBs).
• Elementary bodies reorganize into reproductively
  specialized reticulate bodies (RBs) which then
  change back to infectious elemenatry bodies.
• Completely dependent on the host for ATP.

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Chlamydia

• Gram-negative-like wall but lacks muramic acid
  and peptidoglycan
• Use cross-linking of outer membrane and,
  possibly, periplasmic proteins to achieve osmotic
  stability
• Found mostly in mammals and birds but have been
  recently isolated from spiders, clams and
  freshwater invertebrates

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Chlamydia

• Three recognized human pathogens
• C. trachomatis - causes chlamydia, a sexually
  transmitted disease, trachoma, an eye infection
  that is a frequent cause of blindness and other
  human diseases.
• C. psittaci- causes psittacosis in humans and
  infects many other mammals as well.
• C. pneumoniae - a causative agent of human
  pneumonia

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Spirochetes

• The phylum has one class, Spirochaetes, three
  families, and 13 genera.
• Gram-negative, chemoheterotrophic long flexibly
  helical coiled bacteria.
• Most are free-living and anaerobic, but can be
  symbiotic, or parasitic.
• Distinguished by the presence of flagella running
  lengthwise between the cell membrane and cell
  wall, called axial filaments

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Spirochetes

• The axial filament (a complex of periplasmic
  flagella) lies in a flexible outer sheath (outer
  membrane) outside the protoplasmic cylinder that
  houses the nucleoid and cytoplasm the function
  of the sheath is essential, but unknown.
• Flagellar rotation is responsible for motility by
  an unknown mechnism presumably by rotating the
  outer sheath or flexing the cell for a crawling
  motion.
• Spirochete can move through very viscous
  solutions though they lack external rotating
  flagella.

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Spirochetes

• Exceptionally diverse ecologically and grow in
  habitats ranging from mud to the human mouth.
• Ecologically diverse
• Spirochaeta are free-living, and grow in
  anaerobic and sulfide-rich fresh water and marine
  environments.
• Leptospira is both pathogenic and saprophytic,
  can occupy diverse environments, habitats and
  life cycles.
• Treponema includes the caustive agent of
  syphillis (T. pallidum)
• Borrelia includes the caustive agent of Lyme
  disease (B. burgdorferi)