Microbiology

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Microbiology
Chapter 1 The Microbial World and You
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Microorganisms and Microbiology

• Microbiology is the study of microorganisms
• Microscopic, single cell, cluster, chains
• carry out life processes independently as single
  cells
• Viruses- microscopic, non-cellular, RNA or DNA
• Bacteria and their processes and their effects on
  society, humans, animals and environment
• Two basic themes
• Basic- cellular processes
• Applied practical problems in agriculture,
  health and industry
• Importance of microorganisms
• 1. evolution of oxygen and first cells on early
  Earth
• 2. activities affect the entire web of life on
  Earth

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MICROBES EXIST EVERYWHERE
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Microorganisms and Their Environment

• Microbes exist in populations that occupy a
  location in the environment (habitat)
• Populations of cells rarely live alone and form
  assemblages of different populations (microbial
  communities)
• Microbial communities free swimming or biofilms
  (attached to a surface)
• Interactions between communities may be
• 1. beneficial cooperative feeding efforts
• (waste-nutrient)
• 2. harmful - waste product is inhibitory
• Ecosystem Living organisms together with
  physical and chemical constituents of environment

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Extent of Microbial Life

• Strength is in numbers 5 x 1030 for prokaryotes
  (bacteria)
• Total carbon in this number of small cells equals
  that of all plants on Earth
• Prokaryotic cells
• 1. Constitute the major portion of biomass on
  Earth
• 2. Key reservoirs of essential nutrients for
  life
• Most of the prokaryotes are in oceanic and
  terrestrial subsurfaces

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Microbes and Agriculture

• Nitrogen fixation
• 1. association between plants (legumes) and
  bacteria
• 2. reduce need for fertilizer
• Rumen microbes in cattle and sheep allow them to
  breakdown/digest grass and hay
• Nutrient cycling (C, N, and S)
• Plant and animal diseases

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• 1. Microorganisms and Food
• prevent microbial spoilage of food and food borne
  disease
• Manufacturing of foods
• 2. Microorganisms, energy and environment
• Natural gas (methane)
• Ethanol (biofuel)
• Bioremediation
• 3. Microbes and the future
• Biotechnology-genetic engineering

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Microorganisms are especially useful in research

• 1. Have relatively simple structures
• 2. Large numbers of microbes can be used in an
  experiment to obtain statistically reliable
  results at a reasonable cost
• 3. Reproduce quickly so they are useful for
  studies involving transfer of genetic information

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The prefix "micro" means small, and most microbes
cannot be seen without a microscope. Eukaryotic
microbes are the biggest, generally ranging from
a few micrometers (µ) to many hundreds of µ.
Bacterial cells usually range from 0.5 µ to 5.0
µ (although some bacteria have been found that
are much larger.) Viruses are much smaller,
usually less than 0.1µ. Our eyes cannot resolve
objects smaller than 0.2mm (200µ.) However, if
you squint at a jar of fresh pond water, you can
often just make out some large protists such as
ciliated paramecia.
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Naming organisms

• Binomial nomenclature was created by Carolus
  (Karl) Linnaeus
• 2 name naming (genus and species)
• Use Latin
• Genus is capitalized (Streptococcus)
• Species is small case (aureus)
• Always use italics or underline

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The figure to the left shows the 3-Domain
classification of organisms. Bacteria and
Archaea consist of prokaryotic microbes, whereas
Eukarya consists of eukaryotic microbes as well
as plants and animals.
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There are four major kinds of microbes
bacteria, fungi, protists, and viruses.
This microbe is a type of protist called a
ciliate.
Bacterial cells are prokaryotic, which means they
lack internal membrane bound organelles such as
nuclei and mitochondria. Fungi and protists are
eukaryotic they have a cell nucleus containing
multiple chromosomes, and other membrane bound
organelles. Viruses are not cells at all-- they
are tiny, inert particles containing DNA or RNA
that must infect an appropriate host cell in
order to reproduce and survive.
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Bacteria (singular bacterium)

• Single-celled organisms
• Prokaryotes
• Shapes
• 1. Spherical
• 2. Rod
• 3. Spiral

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Streptococcus sp.
Klebsiella pneumoniae (5,821X)
Treponema pallidum
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Algae (singular alga)

• Single-celled microorganisms
• Eukaryotic
• Nucleus and membrane-bound organelles
• Photosynthetic
• Fresh water and marine environments

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Micrasteria (334X)
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Fungi (singular fungus)

• Single-celled microorganisms (Yeasts)
• Multi-cellular microorganisms (Molds)
• Eukaryotic
• Widely distributed in water and soil as
  decomposers of dead organisms
• Some are important in medicine

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Philobolus crystallinus (50x)
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Viruses

• Acellular entities too small to be seen with a
  light microscope
• Composed of nucleic acid and protein
• Bacteriophage viruses that infect bacteria
• Viroids nucleic acid without a protein coating
• Prions Infectious proteinaeceous particles

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Bacteriophages (35,500x)
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Protozoa (singular protozoan)

• Single-celled, microorganisms
• Eukaryotic
• Have a nucleus (membrane-bound) and other
  intracellular structures
• Found in a variety of water and soil environments

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Amoeba (183X)
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Acanthrocirrus retrirostris (189X).
Helminthes multicellular animal parasites some
life stages are microscopic and pathogenic
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Why have people been so interested in figuring
out what causes disease? The Triumph of
Death by Pieter Breughel, the Elder
Yersinia pestis The black Death is bubonic
plague caused by a bacterium
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History of microbiology

• http//users.stlcc.edu/kkiser/History.page.html
  this site has a time line and pictures of the
  major players in early microbiology
• Cell theory-Hookes discovery marked the
  beginning of this
• Spontaneous generation-life from non-life
• Much early micro work was to either prove or
  disprove this theory
• Biogenesis-living cells come from pre-existing
  cells
• Aseptic technique-germ free
• Golden age of microbiology-began with Pasteurs
  work
• Germ theory of disease-proved by Koch

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Historical Scientists in Microbiology

• 1. Antony van Leeuwenhoek
• 2. Louis Pasteur
• 3. Joseph Lister -antiseptic
• 4. Edward Jenner - vaccination
• 5. Elie Metchnikoff - immunology
• 6. Paul Ehrlich chemotherapy- magic bullets
  - antibiotics
• 7. Alexander Fleming discovered penicillin

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Historical Roots of Microbiology

• -1664 Robert Hooke - cellulae
• -1684 A. V. Leeuwenhoek
• -Ferdinand Cohn founder of bacteriology
• - Louis Pasteur Disproved Spontaneous
  generation, vaccination, pasteurization
• -Robert Koch germ theory, demonstrates that
  specific microorganisms cause specific disease
  (Kochs postulates)
• Isolation of harmful pathogens
• developed techniques that furthered
  advancement of Microbiology

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Anton van Leeuwenhoek (1632-1723) See figure 1.2
page 7
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Unifying Theories of Microbiology

• The Cell Theory All cells are the fundamental
  units of life and carry out all basic functions
  of living things
• The Germ Theory of Disease States that
  microorganisms can invade other organisms and
  cause disease

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Disproof of Spontaneous Generation (Aristotelian
Abiogenesis)

• 1. Francesco Redi flies in the jar
• At the time, prevailing wisdom was that maggots
  formed naturally from rotting meat. In the
  experiment, Redi took eight jars, which he
  divided in two groups of four in the first jar
  of each group, he put an unknown object in the
  second, a dead fish in the last, raw chunk of
  veal. Redi took the first group of four jars, and
  covered the tops with fine gauze so that only air
  could get into it. He left the other group of
  jars open. After several days, he saw maggots
  appear on the objects in the open jars, on which
  flies had been able to land, but not in the
  gauze-covered jars.
• 2. Lazaro Spallanzani boiling sterilization
• Spallanzani researched the theory about the
  spontaneous generation of cellular life in 1768.
  His experiment proved that microbes come from the
  air and that they could be killed through
  boiling. This work paved the way for later
  research by Louis Pasteur.
• 3. Louis Pasteur Swan necked flask experiment
• 4. John Tyndall settling dust experiment in
  air-tight box
• In the lab he developed 'optically pure' (i.e.
  extremely filtered) air. This air contained
  relatively very little or no micro-organisms. He
  compared what happened when he let prepared meat
  sit in such pure air and in ordinary air. The
  preparations in the pure air didn't go putrid,
  unlike the ones in ordinary air. These studies
  extended Louis Pasteur's recent demonstrations
  about germs.

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A swan-necked flask that Pasteur used in
refuting the theory of spontaneous generation
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Pasteurs Further Contributions

1. Developed the technique of pasteurization to kill
   unwanted microorganisms
2. Association of specific organisms with particular
   diseases
3. Development of vaccines

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Louis Pasteur in his laboratory
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BIOGENESIS

• All this eventually leads to Rudolf Virchows
  concept of BIOGENESIS
• That all living cells can only arise from
  pre-existing living cells

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Robert Koch (1843-1910) First proof that
bacteria actually cause some disease
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Kochs Postulates

1. The microbe must be present in every case of the
   disease but absent from healthy organisms
2. The suspected microbe must be isolated and grown
   in a pure culture
3. The same disease must result when the isolated
   microbe is inoculated into a healthy host
4. The same microbe must be isolated again from the
   diseased host

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Techniques for Studying Microorganisms

• Fannie Hesse suggested that agar could be used as
  a solidifying agent
• Richard Petri developed the petri dish which was
  used to contain the solid culture media (agar and
  nutrients)
• Robert Koch used these techniques to isolate the
  bacterium that caused tuberculosis

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Early Contributors to Bacteriology Angelina and
Walther Hesse
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Work Toward Controlling Infections

1. Ignaz Phillip Semmelweis Childbirth fever
   that physicians (who did not routinely disinfect
   their hands at the time) were responsible for
   transmitting puerperal fever from one patient to
   another
2. Joseph Lister Listerine

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Ignaz Philipp Semmelweis (1818-1865) Depicted on
an Austrian 1965 postage stamp
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Joseph Lister Antiseptic Surgery (1869)
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Modern Developments

• Bacteriology-study of bacteria, began with
  Leeuwenhoeks examination of tooth scrapings
• Mycology-study of fungi
• Parasitology-study of protozoa and parasitic
  worms
• Immunology-study of the immune system, began with
  Jenners first vaccine in 1796
• Advanced when Rebecca Lancefield classified
  Streptococcus based on differences in cell wall

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Modern Developments continued

• Virology- Iwanowski and the tobacco mosaic virus
  discovery in 1892 gave it a major boost
• Recombinant DNA technology-use microorganisms to
  manufacture human hormones and other medical
  substances (growth hormone used to come from
  cadavers)
• The technology is also called genetic engineering
  
• 1944 DNA proved to be unit of heredity (Averys
  group
• 1946 Lederberg and Tatum discovered conjugation
• 1953 Watson and Crick created model for DNA
• 1961 Jacob and Monod discovered mRNA leading to
  the understanding of protein synthesis

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Emergence of Special Fields of Microbiology

1. Immunology
2. Virology
3. Chemotherapy
4. Genetics and Molecular Biology

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Elie Metchnikoff (1845-1916) discovers
phagocytosis, which we now know is the way much
of our immune system works
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Electron micrograph of tobacco mosaic virus (
617,000X)
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TOBACCO MOSAIC VIRUS A helical core of RNA
surrounded by a coat consisting of repeating
protein units. The structure of the particles is
so regular that the viruses can be crystallized.
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Paul Ehrlich (1854-1915)
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Sir Alexander Fleming (1881-1955) discoverer of
penicillin the first antibiotic
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Plant scientists using knowledge gained from
research
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Fields of Microbiology
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Genetically engineered bacteria used to
investigate how diet influences cancer risk
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Inspecting plastics made with as much as 40
starch (pieces inside baskets) for signs that
aquatic microbes are degrading them
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DECONTAMINATE WASTES
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Using beating nets to survey for ticks that can
spread disease to livestock and humans
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Keeping pets and domestic animals healthy, as
well as improving their productivity, by means of
advances in veterinary science
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The AIDS Memorial Quilt in Washington, D.C.
November 1996, the last time it was small enough
to be displayed all at once. Over 45,000 panels,
each dedicated to the memory of one victim,
covered 15 city blocks.
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A model of the virus that causes AIDS.