Kingdom Monera
The Bacteria
What are bacteria?
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Very old form of life ~ 3.5 billion years
Extremely abundant ~ 2.5 billion/gram of soil,
found
Live almost everywhere, even where nothing
else can live
Unicellular organisms
No nucleus
Simple cell structure – lacks complex
organelles of higher life forms
How Bacteria Get Food
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Most are heterotrophic, but some are autotrophic
Cyanobacteria – also called blue-green algae are
autotrophic
Photo by: Matthewjparker
http://en.wikipedia.org/wiki/File:Tolypothri
x_(Cyanobacteria).JPG
"Cyanobacteria" by Argonne National Laboratory
Attribution-NonCommercial-ShareAlike License
http://www.flickr.com/photos/argonne/5909383026/
Public Domain – NASA
http://commons.wikimedia.org/wiki/Fil
e:Cyanobacteria_guerrero_negro.jpg
How Bacteria Get Food
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Chemosynthetic bacteria are also
autotrophic - they use sulfur- or ironcontaining compounds to make their
food
Heterotrophic bacteria may be parasites,
or they may eat other organisms, or they
may be decomposers living on dead
organic material.
Bacteria and Oxygen
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Like higher life forms many bacteria
need oxygen to live
Some bacteria do not need oxygen
Some bacteria are actually inhibited or
killed by the presence of oxygen, for
example the tetanus bacterium.
Forms of Bacteria
1. Bacilli – rod-shaped bacteria
(singular – bacillus)
 The first bacteria discovered to cause
disease was a bacillus – Anthrax was
discovered by Koch in 1877
 May form chains (Streptobacillus)
Bacilli
Escherichia coli
Light Micrograph
Escherichia coli
Electron Micrograph
Photo by: Y_tambe
http://commons.wikimedia.org/wiki/File:Escherichia_coli_Gram.jpg
Public Domain: National Institutes of Health
http://commons.wikimedia.org/wiki/File:EscherichiaColi_NIAID.jpg
Forms of Bacteria
2.
Coccus – sphericalshaped bacteria
a.
Streptococcus – chains
of coccus bacteria
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b.
ExampleStreptococcus
pyogenes that causes
strep throat and
scarlet fever and is
the “flesh-eating
bacteria”
Staphlococcus –
grape-like clusters of
coccus bacteria
Streptococcus pyogenes
Public Domain – CDC
http://en.wikipedia.org/wiki/File:Streptococcus_pyogenes.jpg
Staphylococcus
Staphylococcus aureus –
light micrograph
Staphylococcus aureus –
electron micrograph
Photo by Y Tambe
http://en.wikipedia.org/wiki/File:Staphylococcus_aureus_Gram.jpg
Photo by: Janice Carr, Public Domain – CDC
http://en.wikipedia.org/wiki/File:Staphylococcus_aureus_01.jpg
Forms of Bacteria
3. Spiral – shaped
Example – Spirillum sp.
Spirillum
Public Domain: http://en.wikipedia.org/wiki/File:Spirillen.jpg
Forms of Bacteria
4. Filamentous –
mold-like, long,
branching,
threadlike
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Actinomycetes –
primary
decomposers of
plant material
Frankia sp. –
important plant
partners
Streptomyces species: Branching
filaments, abundant aerial mycelia, and
long chains of small spores are visible
Public Domain – CDC
http://commons.wikimedia.org/wiki/File:Streptomyces_sp._PHIL
_2983_lores.jpg
Forms of Bacteria
Some bacteria do not fit into any of the
four basic forms such as
Bifidiobacterium that are Y-shaped
Reproduction in Bacteria
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Bacteria reproduce by a
process known as binary
fission where one cell divides
into two equal cells
1→2 →4 →8 →16 →32 →64
→128 →256 →512 →etc.
Under ideal conditions
reproduction can happen every
20 minutes. Why doesn’t this
usually happen?
Image by: Mcstrother
http://commons.wikimedia.org/wiki/File:Binary_fission2.svg
Structure of Bacteria
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Cell Wall - a tough, rigid
structure that surrounds,
supports, shapes and
protects the cell
• almost all bacteria
have cell walls
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Capsule - An additional
coating/layer surrounding
the cell wall that some
bacteria have
Public Domain: http://commons.wikimedia.org/wiki/File:Average_prokaryote_cell-_en.svg
Structure of Bacteria
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Cell membrane
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Hereditary
Material (DNA) –
not within a
nucleus
Public Domain: http://commons.wikimedia.org/wiki/File:Average_prokaryote_cell-_en.svg
Movement of Bacteria
Many bacteria are motile, meaning
they can move themselves. They
move by means of one or more
flagella. Flagella are long, thin,
whip-like structures on the
outside of a bacterium.
Public Domain – CDC
http://en.wikipedia.org/
wiki/File:Alcaligenes_f
aecalis_PHILstained.jpg
Author: Mike Jones
http://commons.wikimedia.org/wiki/File:Flagella.png
Movement of Bacteria
Non-motile bacteria depend
upon environmental factors to
move them – air currents,
water, physical objects, etc.
Endospores
Under adverse conditions
some bacteria form a
resting cell called an
endospore that can
survive. An endospore
consists of hereditary
material, a small amount
of cytoplasm and a thick
protective outer coat.
Examples: Tetanus and
Anthrax
Clostridium botulinum
vegetative cells and endospores
Public Domain - CDC
http://en.wikipedia.org/wiki/File:Clostridium_botulinum_01.png
Bacteria in Nature
An essential part of the food and energy
relationships that link all life on Earth
• Decomposers free up nutrients needed by
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autotrophs
Small heterotrophs (protists and tiny animals)
feed on bacteria and in turn become food for
larger heterotrophs
Bacteria in Nature
Cyanobacteria were the first oxygen
producers and raised oxygen levels from
1% to 20% allowing oxygen-using
organisms to evolve
Bacteria continue to change their
environment – for example they are the
first colonizers of land after a volcanic
eruption
Symbiosis
Symbiosis = a relationship in which one organism
lives on, near or inside another organism and
at least one of the organisms benefits
 Mutualism = a symbiotic relationship where
both of the organisms benefit
 Parasitism = a symbiotic relationship where
one organism benefits but the other one is hurt
in some way
Bacteria in Nature
Bacteria form extremely important mutualistic
relationships
1. Actinorhizal plants and Frankia bacteria
2. Legumes and Rhizobia bacteria
Both are extremely important relationships where
the bacteria live within the roots of the plants and
change nitrogen gas (N2) into ammonia (NH3) that
the plant can use (called Nitrogen fixation). The
plant gets nitrogen it can use and the bacteria get
food (sugar) from the plant.
Bacteria in Nature
Actinorhizal plants and
Frankia bacteria
Alder Root Nodule
Photo by: Roger Griffith
Public Domain:
http://en.wikipedia.org/wiki/File:An_alder_root_nodule_gall.JPG
Bacteria in Nature
Legumes and
Rhizobia bacteria
Clover Root
Nodules
Photo by: Jeremy Kemp
http://en.wikipedia.org/wiki/File:Nitro
genFixingNodulesOnClover.jpg
Root Nodules on
Medicago italica
http://en.wikipedia.org/wiki/File:Medicago_ita
lica_root_nodules_2.JPG
Medicago italica is related to alfalfa.
Bacteria in Nature
Bacteria form extremely important mutualistic
relationships
3. Bacteria living in the digestive systems of many
animals including all ruminants, horses, termites, etc.
digest plant materials that the animal can’t (cellulose).
Bacteria and Humans
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Food – used to make yogurt, cheese, soy
sauce, etc. but also caused food spoilage
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Food spoilage can be prevented for long periods by
the canning process
Pasteurization (heating to kill bacteria) is used to
prevent disease transmission (tuberculosis) and
increase shelf life
Fuel – methane production, also responsible
for petroleum production
Environmental Cleanup – treat sewage,
cleanup oil spills
Bacteria and Humans
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Health – necessary in intestines where they
make vitamins and protect against bad
bacteria
Medicine – provide many antibiotics but cause
many diseases (diphtheria, tetanus, cholera,
strep throat, bubonic plague, staph infections,
Lyme disease, some pneumonias)
Industry – many uses including tanning leather
and extracting valuable metals from rocks but
can also damage industrial materials