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Are found in more varied habitats and environments than any other living organism ... Transmitted by insects (ticks, mites, human body louse) ... – PowerPoint PPT presentation

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Title: Bacteria

Ancient bacteria
  • Lack of a membrane bound nucleus
  • No membrane bound organelles
  • Prokaryotes
  • Most are unicelluar
  • Types
  • Ancient bacteria
  • True bacteria

True bacteria
Size of Bacteria
  • One pound of fertile soil may contain as many as
    50 million bacteria
  • Measured in microns

Habitats of Bacteria
  • Are found in more varied habitats and
    environments than any other living organism
  • Exist on animals and plants
  • Exist in soil, ocean, desert, hot springs, snow

3 basic Bacteria Shapes
  • 1. Coccus
  • Spherical or oval shape
  • Average size is about 0.5 1.0 micrometer (1
    micrometer 1/1,000,000 of a meter)
  • 2. Bacillus
  • 3. Spirilla
  • Spiral shaped

Bacteria Shapes
Coccus Bacteria
  • Diplococcus- pair of cocci
  • Staphylococcus- clusters of cells, irregular
    shapes like grapes (Staphylococcus aureus)
  • Streptococcus- chain of cocci (Streptococcus
  • Tetrad- square of 4 cocci
  • Sarcina- cube of 8 cocci

Bacteria Structure
  • Capsule-
  • Layer of polysaccharides (sometimes proteins)
    that protects the bacteria cell
  • Not present in all bacteria cells
  • Often associated with pathogenic bacteria because
    it serves as a barrier against phagocytosis by
    white blood cells
  • Produces serious infection
  • Pneumonia organism

Structure - continued
  • Plasma membrane
  • Lipid bilayer
  • Numerous proteins moving within layer responsible
    for transporting ions, nutrients and waste
  • Cell wall
  • Composed of peptidoglycan
  • Cell wall maintains the overall shape of a
    bacteria cell

Structure - continued
  • Pilli-
  • Hollow, hair-like structures made of protein that
    allow bacteria to attach to other cells
  • Slime layer
  • Excreted by the cell under certain conditions
    when the environment is unfavorable
  • Endospore
  • Non-reproductive structure
  • Dormant form of a bacteria
  • Protects cell from high temperatures, most
    disinfectants, low energy radiation, drying out

Bacteria cells lack
  • Nucleus
  • Nuclear membrane
  • Mitochondria
  • Bacterial cells use enzymes found on the cell
    membrane instead

  • Flagella
  • Can have one or more flagella arranged in clumps
    or spread all over the cell
  • The flagellum is a rigid structure that rotates
    like a propeller
  • Sliding
  • Has direction like a floor buffer
  • Brownian movement
  • Involves mostly cocci forms
  • Collisions of bacterial particles with other
    molecules in a fluid environment

How fast are they?
Ideal Conditions for Bacterial Growth
  • Temperature
  • 80F to 100F
  • Cause of human infections (98.6F body temp.)
  • Moisture
  • Most active bacterial cells are 90 water
  • Prolonged dryness will kill bacteria of most
  • Darkness
  • Sunlight retard growth
  • UV radiation kills cells
  • Food Source
  • Most pathogenic bacteria require living tissues

Thursday, May 1
  • Do Now have out bacteria outlines
  • 1. Continue with Bacteria
  • 2. Bacteria CD Rom
  • 3. Begin work on rest of packet with viruses
  • HW- Objectives due Friday

Bacterial Nutrition - Heterotrophic bacteria
  • Utilizes oxygen in growth
  • Obtain energy from organic compounds
  • Saprophytes- live off of dead organic matter
  • Parasites- live off of animals or plants and
    cause damage or even death
  • Have the ability to withstand the hosts defense

Bacterial Nutrition - Autotrophic bacteria
  • Use carbon dioxide as their source of carbon for
  • Obtain energy from light or inorganic compounds
  • Phototrophic bacteria- use photosynthesis to make
    ATP from light energy
  • Chemosynthetic bacteria- use organic and
    inorganic chemicals as their energy source

Bacterial Respiration
  • Obligate aerobes- require oxygen for respiration
  • Examples
  • Diptheria- affects the throat and respiratory
    system in humans
  • Tuberculosis- spreads to organs and other systems
    by blood or lymph
  • Cholera- infects intestines, associated with
    contaminated water

Bacterial Respiration
  • Obligate anaerobes- cannot grow in the presence
    of oxygen
  • Examples
  • Tetanus- lockjaw affects the neuromuscular
  • Botulism- food born botulism infects intestines
    and passes into the bloodstream

Bacterial Respiration
  • Facultative anaerobes-
  • Grow best as aerobes, but can grow as anaerobes

Serratia cells found in soil
Gram Staining
  • Gram positive
  • Contain a lot of peptidoglycan in the cell wall
  • Gram negative
  • Less peptidoglycan in the cell wall
  • Contain a second membrane external to the cell
    wall that is chemically different than the cell

Gram Staining
Bacterial Reproduction
  • Transverse Binary Fission
  • Simpler than cell division
  • Can occur in 20 minutes to 20 hours depending on

Reasons for the Death of Bacteria Cells
  • Cells cannot resume cell division once in a new
  • Crowding
  • Food competition
  • Metabolic wastes
  • Colony formation- stability or death

Bacterial Genetic Recombination
  • Transduction-
  • Bacteria genes are carried by a donor cell to a
    recipient cell by a bacteriophage

Bacterial Genetic Recombination
  • Conjugation-
  • Genetic information is passed among
  • Important adaptation for bacteria to gain
    resistance against antibiotics

Bacterial Genetic Recombination
  • Transformation-
  • The taking of DNA from a donor bacterium cell to
    another recipient bacterium cell
  • Griffiths experiment

Spore Formation
  • When conditions are unfavorable, bacteria can
    form spores to protect themselves until
    conditions become favorable again
  • This process starts in a resting stage where the
    endospores are formed in the mother cell when
    nutrients are limited to ensure survival of the

Spore Formation
  • Endospores are used because they are
  • Highly resistant to adverse conditions
  • Little to no metabolic activity takes place
  • Hard to kill
  • Anaerobic
  • Can remain in the endospore state for as long as
    30 years and still be effective

Beneficial Bacteria in the Soil
  • Green plants absorb minerals from the soil
  • Use these minerals in synthesizing organic
  • Animals consume plants and rearrange compounds
    for their own needs
  • Remains of living organisms are left in complex
    forms that must be broken down
  • Decomposers will break down tough materials, like
    cellulose and chitin
  • Materials later are returned to the Earth and

Bacteria in Industrial Processes
  • Making of vinegar-
  • Yeasts ferment sugar into fruit juice that is
    changed into alcohol
  • Bacteria oxidize the alcohol and change it to
    acetic acid

Bacteria in Industrial Processes
  • Making of sauerkraut
  • Cabbage leaves are shredded and placed in an
    airtight jar
  • Anaerobic bacteria (lactobacillus) ferment the
    sugar in cabbage leaves and converts it to lactic

Bacteria in Industrial Processes
  • Tanning of leather
  • In ancient times, animal skin was shaved and
    cleaned and pigeon or hen dung was infused
    followed by an infusion of dog dung. This set
    off a fermentation reaction and softened the

Bacteria in Industrial Processes
  • Retting of Flax
  • Flax- woody stem of the flax plant is used to
    make linen
  • Takes 4 to 6 days in warm water tanks and up to 3
    weeks in cold water or dew. Water helps soil
    bacteria penetrate the woody stems. The break
    down the pectins that hold together the woody and
    fibruous portions of the plant. Then is dried in
    open fields

Bacteria in Industrial Processes
  • Silage-
  • Contains organic acids that are the products of
    sugar and starch fermentation. Anaerobic
    condition that prevents plant decay and permits
    bacteria (lactobacillus) to ferment sugar in the

Bacteria in Industrial Processes
  • Tobacco-
  • Curing process
  • Brings out the flavor and smell of tobacco.
    Bacteria ferment carbohydrates in the moist
    leaves producing special flavors

Bacteria in the Dairy Industry
  • Milk
  • Ideal culture medium for bacteria. Most
    countries require the destruction of unwanted
    microorganisms and pathogenic bacteria
  • Pasteurization
  • Destruction of disease-causing bacteria in milk,
    fruit juices, wine and other malt beverages by
  • Destroys milk-souring bacteria
  • Temperature needs to be high enough to kill
    harmful bacteria. Flash heat method (161F for 15
    minutes) is more effective than holding methods
    (145F for 30 minutes)

Bacteria in the Dairy Industry
  • Butter
  • Raw cream is separated from whole milk and is
    pasteurized. Various bacteria are used to ripen
    and adjust the pH of the cream to achieve the
    desired flavor. The liquid is poured off and
    buttermilk is made from this liquid.
  • Cheese
  • Use whole or skim cow or goat milk. Bacteria is
    added to form lactic acid to cause curdling.
    Cottage cheese curd is eaten while moist and
    unripened. Cream cheese butter fat is added to
    the curd. Other cheeses processed salted and
    pressed to remove moisture then ripened.

Food Spoilage and Preservation
  • Preservation of food destroys all bacteria
    present and seals the food in the appropriate
    container (canning can be preserved indefinitely
    if done correctly)
  • Environmental control maintain foods under
    appropriate conditions to inhibit bacterial
    growth and activity. Salt curring plasmolysis
    of cells (meat- prevents botulism)
    Refrigeration retards growth and reproduction of
    bacteria Quick freezing temps of 0 to -10 to
    -15 degrees F ceases all bacterial activity
    Dehydration removes water from food so bacteria
    cannot grow Chemicals/ Radiation food can be
    kept indefinitely

Bacterias Relatives
  • Rickettsiae between bacteria and viruses
  • Bacteria- cellular and reproduce by fission
  • Virus- grow and reproduce only in living cells
  • Transmitted by insects (ticks, mites, human body
  • Live in the carrier hosts intestines but do not
    cause the disease
  • Diseases caused Rocky Mountain Spotted Fever,
    Trench Fever, and mysterious Q fever

Bacterias Relatives
  • Spirochetes between bacteria and protozoans
  • Live in the human body and cause disease
  • Pathogenic
  • Live in the bloodstream and invade the nervous
  • Spread in material that is discharged from
    lesions or eruptions of the skin and mucous
    membranes during the early stages of the disease

Edward Jenner
  • First experimental vaccination for cow-pox virus
    to build immunity against smallpox. Coined the
    term vaccination from the Latin vacca meaning cow

Louis Pasteur
  • germ theory of disease
  • Weakened forms of microbe to be used as
  • Rabies was caused by something so small and it
    was later used to treat humans
  • Developed pasteurization to destroy the bacteria
    in food without harming the food
  • Studied why alcohol contaminated during

Alexander Fleming
  • Discovered lysozyme (a protein found in healthy
    noses and tears)
  • Used a culture of his own nasal mucus to
    inhibited the growth of Staphylococcus cultured
    from the same mucus
  • Found a strain of bacteria that was particularly
    sensitive to lysozymes

Bodys defenses against bacteria
  • Neutralizing antibodies block viruses from
    attaching and entering the host
  • Virus specific antibodies can act against
    proteins on the virus surface
  • Overuse of antibodies can lead to the development
    of resistant bacteria