Bacteriology BIO 309 Summer 2003

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Bacteriology BIO 309 Summer 2003

• Dr. H. DeHart
• 215 TCNW
• 745-5136
• Heather.DeHart_at_wku.edu

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Introduction to Microbiology - Chapter 1

• Microbiology The study of microorganisms
  (large, diverse group of cells living
  individually or as clusters, includes the
  viruses, which are microscopic but not cellular)

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Basic vs. Applied Microbiology

• Basic Microbiology Properties that all cells
  have in common, short life cycles, biochemical
  and genetic studies.
• Applied Microbiology Practical problems in
  medicine (diseases vs. microbes living in assoc.
  with the body without causing harm), agriculture
  (soil fertility, etc.), and industry (production
  of antibiotics, food products, etc.).

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Importance of Microorganisms

• Precursors for higher organisms
• Sustain higher organisms and the environment by
• Production of oxygen
• Recycling of key nutrients
• Degradation of organic matter

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The Cell (What all cells have in common)

• Fundamental unit of life
• Has a cell membrane to separate the contents of
  the cell from the outside world
• Has a nucleus or nucleoid that contains the
  genetic material (DNA) for reproduction
• Contains cytoplasm, where the machinery for cell
  growth and function are present

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The Cell (continued)

• Is made up of 4 chemical components
• proteins
• nucleic acids
• lipids
• polysaccharides
• Regulates what comes and goes is an open system

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The Cell (continued)

• Carries out metabolism (takes up chemicals from
  the environment, transforms them into energy
  usable by the cell, and eliminates waste
  products)
• Communicates (responds to chemical signals in the
  environment)
• Is capable of differentiation, movement, and
  evolution
• Refer to Fig. 1.3 in the text

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How and Where do Microbes Live?

• Cells live in nature associated with other cells
  in groups called populations.
• The location in an environment where a microbial
  population lives is called the habitat.
• In nature, populations of cells usually live and
  interact with other populations of cells in
  groups called microbial communities.
• Living organisms together with the physical and
  chemical constituents of their environment an
  ecosystem.

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The Extent of Microbial Life

• Prokaryotes (bacteria) constitute the major
  portion of biomass on Earth and are key
  reservoirs of essential nutrients for life.
• Most prokaryotes live underground in oceanic and
  terrestrial subsurfaces instead of on the surface
  of the Earth.

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Harmful Microorganisms

• Microbes cause infectious diseases such as
  influenza, pneumonia, tuberculosis,
  gastroenteritis, infant diseases, and diphtheria.
• For developed countries, these diseases were a
  much bigger problem in the past than they are
  today. Why is this? Also, why are they still a
  major problem for developing countries? Refer to
  Fig. 1.7 in the text.

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Harmful Microorganisms (continued)

• What populations of people are currently most
  susceptible to or affected by microbial diseases
  in developed countries? Why?
• It is important to prevent spoilage of foods by
  microbes by methods such as canning, freezing,
  drying, pickling, and salting.
• Refer to Fig. 1.7 in the text

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Beneficial Microorganisms

• Agriculture
• Legumes form nodules on their roots, in which
  microbes convert N2 to fixed N compounds that the
  plant can use. Microbes also cycle other key
  nutrients.
• Farm animals (cattle, sheep) have a digestive
  organ called a rumen in which microbes digest
  grass and hay into usable compounds for the
  animal.

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Beneficial Microorganisms (continued)

• Food industry Products manufactured via
  microbial activity cheese, yogurt, buttermilk,
  sauerkraut, pickles, some sausages, baked goods
  (ex. breads), alcoholic beverages, soy sauce.
• Energy Production Microbes convert domestic and
  animal waste and surplus grain to biofuels such
  as methane (natural gas) and ethanol ( green
  power).

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Beneficial Microorganisms (continued)

• Environment Microbes can clean up pollution
  through a process called bioremediation (their
  metabolism converts toxic compounds to innocuous
  compounds).
• Biotechnology Genetically modified microbes are
  specially designed to synthesize certain products
  of high commercial value, ex. human insulin.
• Refer to Fig. 1.6 in the text

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The History of Microbiology

• 1664 - Robert Hooke described the fruiting
  structures of molds.
• 1684 - Antoni van Leeuwenhoek built the first
  microscope and was the first person to see
  microorganisms, he called them wee animalcules.
• 1850 - Ferdinand Cohn founded bacteriology (the
  study of bacteria), discovered the genus Bacillus
  and endospores.

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The History of Microbiology (continued)

• 1884 - Robert Koch discovered the mechanism of
  transfer of infectious disease between
  individuals, known as Kochs Postulates (Germ
  Theory of Disease). Refer to Fig. 1.12 in the
  text.
• 1885 - Louis Pasteur dispelled the myth of
  Spontaneous Generation. Refer to Fig. 1.11 in
  the text. What did Pasteurs discoveries lead to?

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Kochs Postulates
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Pure Cultures

• Developed by Robert Koch.
• Premise To link a specific microbe to a
  specific process (ex. disease), the organism must
  first be isolated in pure culture.
• Koch first developed nutrient sources on which to
  grow bacteria, ex. potato slices, gelatin. Why
  is it important to be able to grow bacteria on
  solid medium?
• Bacterial colonies can arise from a single
  bacterial cell and have characteristic shape and
  color. Refer to the quote by Koch on p. 15 of
  the text.

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Agar

• 1884 - Walter Hesse first used agar is a
  solidifying agent.
• Agar is composed of a polysaccharide derived from
  red algae.
• Agar liquifies at 55C as opposed to gelatin,
  which is liquid at 37C (98.6F or body temp.),
  the optimum temp. at which most human pathogens
  (disease-causing microbes) grow. Why is this
  important?

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Petri Dish

• 1887 - Richard Petri modified Kochs flat plate
  technique and designed the Petri dish.
• Advantages
• stackable
• can be sterilized separately from the medium (ex.
  nutrient agar)
• cover prevents contamination
• colonies formed on the surface are fully exposed
  to air and easily manipulated
• currently made of glass sterilized by dry heat or
  plastic sterilized by a gas sterilant.

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Metabolically Significant Actions of
Microorganisms

• 1889 - Sergei Winogradsky proposed the concept of
  chemolithotrophy, the oxidation of inorganic
  compounds coupled to the release of energy.
• Winogradsky also concluded that these organisms
  were autotrophs (self-feeding) obtained their
  carbon from CO2 in the air.

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Enrichment (or Selective)Culture

• 1901 - Martinus Beijerinck proposed selecting
  specific microbes from a natural sample through
  the use of specific culture media and incubation
  conditions that favored growth of only one type
  or a physiologically related group of organisms.
• Beijerinck also described the first virus (TMV)
  small (escaped filtration), no bacterial but
  became incorporated into plant cells, requiring
  them to reproduce.

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Development of Subdisciplines of Microbiology -
Applied

• Medical Microbiology - study of bacterial
  pathogens
• Immunology - determination of the mechanisms by
  which pathogens infect the body and are resistant
  to the bodys defenses.
• Agricultural Microbiology - microbial processes
  in the soil that are beneficial or harmful to
  plant growth.

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Development of Subdisciplines of Microbiology -
Applied (continued)

• Industrial Microbiology - important uses of
  microbes, ex. synthesis of antibiotics and
  commodity chemicals.
• Aquatic Microbiology - microbial processes in
  bodies of water (lakes, rivers, oceans, etc.).
  One branch deals with processes for treating
  sewage and providing safe drinking water.
• Microbial Ecology - biodiversity and activities
  of microbes in their natural environments.

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Development of Subdisciplines of Microbiology -
Basic

• Microbial Systematics - discovery and
  classification of new microorganisms.
• Microbial Physiology - study of the nutrients
  that microbes require and the products they make.
• Cytology - study of the physical and chemical
  structure of microbes.

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Development of Subdisciplines of Microbiology -
Basic (continued)

• Microbial Biochemistry - study of the complement
  of microbial enzymes and the chemical reactions
  they carry out.
• Virology - the study of viruses. Viruses that
  infect bacteria are called bacteriophages.
• Biotechnology - introduction of foreign DNA into
  bacteria and control of its replication and
  characteristics.