Chapter 19: Bacteria

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Chapter 19 Bacteria
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How Human are you?

• There are more microbial cells in our bodies than
  there are human cells!
• Of the 100 trillion cells that make-up the human
  body 90 trillion are bacterial
• Humans are 90 Bacterial
• Everyone has about 1 kg in weight of bacteria in
  their gut.
• Each gram of feces contains 100,000,000,000 (100
  billion) microbes.
• Human adults excrete their own weight in fecal
  bacteria every year.

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• Classifying Prokaryotes
• DOMAIN BACTERIA Kingdom Eubacteria
• Single-celled prokaryote
• Have peptidoglycan (protein carbohydrate) cell
  walls
• Can form colonies of clumps or filaments.
• Three basic shapes Cocci (round), bacilli (rod)
  spirilla (spiral)

Strepto occurs in chains.
Staphylo occurs in clusters..
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Cell wall protects the cell gives it
shape. Outer membrane protects the cell against
some anibiotics (only present in
gram-negative) Cell membrane regulates movement
of materials into out of the cell contains
enzymes important to cellular respiration. Plasmid
circular piece of DNA that contains some genes
obtained through genetic recombination. Capsule
Slime layer protect the cell assist in
attaching the cell to other surfaces.
Basic Structure
Ribosome
Cell Membrane
Cell Wall
Pilli
DNA (circular)
Peptidoglycan
Flagella
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• Classifying Prokaryotes
• DOMAIN ARCHAEA Kingdom Archaebacteria
• Genes that resemble eukaryotic genes some that
  resemble prokaryotes.
• Have unusual lipids in their cell membranes
• Found in EXTREME environments!
• Cell walls lack peptidoglycan
• Have introns in their DNA
• Single-celled prokaryote

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• Archaebacteria
• Methanogens
• Convert H2 CO2 into methane CH4
• Anaerobic bacteria
• Found in bottoms of swamps, sewage intestinal
  tracts of animals.
• Extreme Halophiles
• Salt loving
• Found in Great Salt Lake Dead Sea
• Thermoacidophiles
• Live in extreme acidic hot environment

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• Prokaryote Evolution
• Fossil Evidence indicates bacteria existed about
  3.5 billion years ago.
• Eukaryotes existed about 2.5 billion years ago.
• Bacteria evolved to adapt to almost any
  environment, from ocean trenches to thermal
  vents.

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• Identifying Prokaryotes
• Prokaryotes are identified by characteristics
  such as
• the way they obtain energy
• shape
• type of cell wall
• the way they move

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V. Ways Bacteria are Identified

• I. Shapes of Bacteria
• a. Bacilli - rod-shaped

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• b. Cocci - round shaped
• Staphylococcus - cocci in
• clusters
• Streptococcus - cocci in chains
• Diplococcus - cocci in pairs

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Spirilla - spiral shaped Ex Treptonema
pallidum
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Metabolic Diversity Chemoheterotrophs organisms
that must take in organic molecules for both
energy and a supply of carbon. Photoheterotrophs
organisms that are photosynthetic, but still
need to take in organic compounds as a carbon
source. Chemoautotrophs make organic carbon
molecules from carbon dioxide and other inorganic
compounds using energy from chemical
reactions. Photoautotrophs use energy from
sunlight to convert carbon dioxide and water to
carbon compounds.
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Releasing Energy Obligate aerobes organisms
that require a constant supply of oxygen in order
to live. EX Mycobacterium tuberculosis, the
bacterium that causes tuberculosis. Obligate
anaerobes do not require oxygen some may be
killed by O2! EX Clostridium botulinum, found
in soil and can grown in canned food causing
fatal food poisoning. Facultative anaerobes
can survive with or without O2. EX E. coli, can
live in the large intestines and contaminated
water.
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Growth Reproduction Binary Fission bacterium
doubles in size, it replicates its DNA and
divides in half.
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Growth Reproduction Conjugation the process
by which two living bacteria bind together and
one bacterium transfers genetic information to
the other.
Sex pili
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Growth Reproduction Endospore protects the
cell against harsh environmental conditions, such
as heat and drought. May allow the bacterium to
survive for thousands of years.
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• Importance of Bacteria
• Decomposers break down the nutrients in dead
  matter atmosphere.
• Nitrogen Fixing Bacteria (Nitrogen fixation)
• Live freely symbiotically with plants
• Rhizobium converts N2 into a form of nitrogen
  plants can use.
• Found in legumes (bean type plants)

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• Importance of Bacteria
• Phylum Cyanobacteria
• Photosynthetic
• Encased in jelly-like substance cling together
• Contain enzymes for fixing atmospheric nitrogen
  make it available to plants.
• Some thrive on phosphates nitrates in lakes
  ponds.

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Importance of Bacteria Phylum Cyanobacteria Eutrop
hication or Population Bloom the sudden
increase in the number of cyanobacteria due to a
high availability of nutrients. When
cyanobacteria die, they are decomposed by
heterotrophic bacteria. This increase in
heterotrophic bacteria depletes O2 in the water,
harming other organisms that live there.
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• Human Uses of Bacteria
• Food baking beverages
• Clean up oil spills, rivers streams
• Make pharmaceuticals
• Aid in digestion

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Bacteria Disease Pathogen bacteria that cause
disease or a disease causing agent. Exotoxins
toxic proteins secreted by bacterial cells,
includes some of the most potent poisons
known. Clostridium botulinum one gram of the
exotoxin that causes botulism could kill
1,000,000 people! Staphylococcus aureus
harmless, found on skin if it enters the body
through a wound it can cause layers of skin to
slough off, vomiting, severe diarrhea deadly
toxic shock syndrome.
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Bacteria Disease Endotoxins are NOT
secretions but components of cell walls in
bacteria glycolipids, which are large molecular
complexes of polysaccharides lipids. All
endotoxins induce the same general symptoms
fever, aches and sometimes a dangerous drop in
blood pressure (shock). Salmonella produces
endotoxins that cause food poisoning
typhoid fever.
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• Bacteria Disease
• Lyme Disease
• Most widespread pest carried disease in U.S.
• Caused by Borrelia burgdorferi, a bacterium
  carried by ticks that live on deer field mice.
• Antibiotics can cure the disease if administered
  within a month of exposure.
• If untreated, it can lead to arthritis, heart
  disease nervous disorders.

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Bacteria Disease Yersinia pestis the
bacterium that causes bubonic plague throughout
Europe. Carried by fleas. It also played a role
in battle, when armies hurled the bodies of
plague victims into enemy ranks.
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• Bacteria Disease
• Bacillus anthracis
• Found naturally in soil where grazing animals
  such as sheep, cattle goats are located.
• Easy to obtain, grow it forms hardy endospores
  that can survive for years.
• Upon entering the bloodstream, anthrax will
  actively metabolize multiply.
• Anthrax will release 3 proteins that combine to
  form a toxin that destroys body tissues cells
  of the immune system.
• Modes of entry cutaneous, inhalation, ingestion

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Bacteria Disease Bacillus anthracis
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Bacteria Disease
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Antibiotics Antibiotics are drugs that combat
bacteria by interfering with various cellular
functions Some bacteria are antibiotic-resistant
and destroy antibiotics, or prevent entry of the
antibiotic into the cytoplasm.
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Antibiotics Bacteria can be tested for their
sensitivity to antibiotics by growing them in a
petri dish with paper disks containing different
antibiotics. As the antibiotics diffuse into the
agar, the bacterias growth will be inherited by
the antibiotics if the bacteria are sensitive to
that antibiotic.