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					Archaebacteria and Eubacteria
 Bacteria are of
  immense importance
  because of their rapid
  growth, reproduction,
  and mutation rates,
  as well as, their ability
  to exist under adverse
 The oldest fossils
  known, nearly 3.5
  billion years old, are
  fossils of bacteria-like
   Bacteria can be autotrophs or hetertrophs.

   Those that are classified as autotrophs are
    either photosynthetic, obtaining energy
    from sunlight or chemosynthetic,
    breaking down inorganic substances for
    energy .
   Bacteria classified as
    heterotrophs derive
    energy from breaking
    down complex
    organic compounds in
    the environment.
    This includes
    saprobes, bacteria
    that feed on
    decaying material
    and organic
    wastes, as well as
    those that live as
    parasites, absorbing
    nutrients from living
   Depending on the
    species, bacteria can
    be aerobic which
    means they require
    oxygen to live

   anaerobic which
    means oxygen is
    deadly to them.
                        Green patches are green sulfur
                        bacteria. The rust patches are
                        colonies of purple non sulfur
                        bacteria. The red patches are purple
                        sulfur bacteria.
 These Archebacteria
 are anaerobes. They
 make methane
 (natural gas) as a
 waste product. They
 are found in swamp
 sediments, sewage,
 and in buried landfills.
 In the future, they
 could be used to
 produce methane as a
 byproduct of sewage
 treatment or landfill
 These are salt-loving Archaebacteria that grow
 in places like the Great Salt Lake of Utah or salt
 ponds on the edge of San Francisco Bay. Large
 numbers of certain halophiles can turn these
 waters a dark pink. Pink halophiles contain a
 pigment very similar to the rhodopsin in the
 human retina. They use this visual pigment for a
 type of photosynthesis that does not produce
 oxygen. Halophiles are aerobes, however, and
 perform aerobic respiration.
Extreme halophiles can live in extremely salty environments. Most
are photosynthetic autotrophs. The photosynthesizers in this
category are purple because instead of using chlorophyll to
photosynthesize, they use a similar pigment called
bacteriorhodopsin that uses all light except for purple light,
making the cells appear purple.
  These are Archaebacteria from hot springs and
  other high temperature environments. Some can
  grow above the boiling temperature of water.
  They are anaerobes, performing anaerobic
Thermophiles are interesting because they contain
  genes for heat-stable enzymes that may be of
  great value in industry and medicine. An
  example is taq polymerase, the gene for which
  was isolated from a collection of Thermus
  aquaticus in a Yellowstone Park hot spring. Taq
  polymerase is used to make large numbers of
  copies of DNA sequences in a DNA sample. It is
  invaluable to medicine, biotechnology, and
  biological research. Annual sales of taq
  polymerase are roughly half a billion dollars.
  This is a group of bacteria
  that includes some that are
  single cells and some that
  are chains of cells. You may
  have seen them as "green
  slime" in your aquarium or in
  a pond.

Cyanobacteria can do
  "modern photosynthesis",
  which is the kind that makes
  oxygen from water. All plants
  do this kind of
  photosynthesis and inherited
  the ability from the
Cyanobacteria were the first organisms on Earth to
do modern photosynthesis and they made the first
oxygen in the Earth's atmosphere.
   Bacteria are often
    maligned as the
    causes of human and
    animal disease.
    However, certain
    bacteria, the
    produce antibiotics
    such as streptomycin
    and nocardicin.
   Other Bacteria live symbiotically in the
    guts of animals or elsewhere in their

   For example, bacteria in your gut produce
    vitamin K which is essential to blood clot
   Still other Bacteria live
    on the roots of certain
    plants, converting
    nitrogen into a usable
   Bacteria put the tang
    in yogurt and the sour
    in sourdough bread.

   Saprobes help to
    break down dead
    organic matter.

   Bacteria make up the
    base of the food web
    in many
                       Streptococcus thermophilus in yogurt
   Bacteria are prokaryotic and unicellular.

   Bacteria have cell walls.

   Bacteria have circular DNA called plasmids

   Bacteria can be anaerobes or aerobes.

   Bacteria are heterotrophs or autotrophs.

   Bacteria are awesome!
   Bacteria can reproduce sexually by conjugation or
    asexually by binary fission.
   Bacteria can survive
    conditions by
    producing an
Shapes of Bacteria
Penicillin, an antibiotic, comes from molds of the
genus Penicillium Notice the area of inhibition
around the Penicillium.
   Penicillin kills bacteria by making holes in their
    cell walls. Unfortunately, many bacteria have
    developed resistance to this antibiotic.
   The Gram stain, which divides most
    clinically significant bacteria into two main
    groups, is the first step in bacterial

   Bacteria stained purple are Gram + - their
    cell walls have thick petidoglycan and
    teichoic acid.

   Bacteria stained pink are Gram – their cell
    walls have have thin peptidoglycan and
    lipopolysaccharides with no teichoic acid.
In Gram-positive bacteria, the purple crystal violet stain is
trapped by the layer of peptidoglycan which forms the outer
layer of the cell. In Gram-negative bacteria, the outer
membrane of lipopolysaccharides prevents the stain from
reaching the peptidoglycan layer. The outer membrane is then
permeabilized by acetone treatment, and the pink safranin
counterstain is trapped by the peptidoglycan layer.
The Gram stain has four steps:
 1. crystal violet, the primary stain:
  followed by

   2. iodine, which acts as a mordant by
    forming a crystal violet-iodine complex,

   3. alcohol, which decolorizes, followed by
    4. safranin, the counterstain.
Is this gram stain positive or negative?
          Identify the bacteria.
Is this gram stain positive or negative?
Identify the bacteria.
   Gram staining tests the bacterial cell wall's
    ability to retain crystal violet dye during solvent
   Safranin is added as a mordant to form the
    crystal violet/safranin complex in order to render
    the dye impossible to remove.
   Ethyl-alcohol solvent acts as a decolorizer and
    dissolves the lipid layer from gram-negative
    cells. This enhances leaching of the primary
    stain from the cells into the surrounding solvent.
    Ethyl-alcohol will dehydrate the thicker gram-
    positive cell walls, closing the pores as the cell
    wall shrinks.
   For this reason, the diffusion of the crystal
    violet-safranin staining is inhibited, so the
    bacteria remain stained.