Introductory Microbiology

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Introductory Microbiology

• Dr. Heather Townsend
• Summer 2009

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Microbiology

• The study of of organisms (microorganisms or
  microbes) too small to be seen without
  magnification
• This includes
• Bacteria
• Viruses
• Fungi
• Protozoa
• Helminths (worms)
• Algae

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The Microbes

• 1. Bacteria
• Single-celled organisms
• Various shapes
• Spherical
• Rod
• Spiral shapes
• Cellular
• Lack membrane-enclosed cellular structures
• Widely distributed in nature

Klebsiella pneumoniae, bacteria that causes
pneumonia in humans
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The Microbes

• 2. Viruses
• Acellular
• Composed of nucleic acid and a few proteins
• Replicate themselves to display other properties
  of living organisms when they invade living cells

Bacteriophages observed at 35,500X
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The Microbes

• 3. Fungi
• Yeasts and molds
• Single-celled, microscopic
• Mushrooms
• Multicellular, macroscopic
• Cell nucleus and other cellular structures
• Absorb nutrients from their environment
• Widely distributed in water and soil
• Act as decomposers of dead organisms

Philobolus crystallinus, fruiting bodies of this
fungus
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The Microbes

• 4. Protozoa
• Single-celled, microscopic organisms
• Have at least one nucleus and many cellular
  structures
• Obtain food by engulfing or ingesting smaller
  organisms
• Most can move
• Found in many different environments

Amoeba
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The Microbes

• 5. Misc.
• Large, multicellular
• Worms
• Helminths
• Arthropods
• Insects

Tapeworm Head
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The Microbes

• 6. Algae
• Single-celled microscopic organisms
• Have a nucleus and many membrane-enclosed
  cellular structures
• Photosynthesize their own food
• Widely distributed in fresh and salt water
• Important source of food for other organisms

Micrasterias, a green algae living in fresh
water.
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Branches of Study Within Microbiology

• Immunology
• studies immune chemicals and cells that are
  produced in response to infection
• Public health microbiology epidemiology
• aim to monitor and control the spread of diseases
  (CDC)
• Food, dairy and aquatic microbiology
• examine the ecological and practical roles of
  microbes in food and water
• Biotechnology
• ranges from bread making to gene therapy
• Genetic engineering recombinant DNA technology
  
• altering the genetic makeup of organisms

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Microbes Are Involved In

• nutrient production energy flow
• i.e., photosynthesis
• decomposition and nutrient recycling
• production of foods, drugs vaccines
• bioremediation
• causing disease

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Impact of Pathogens

• Pathogens
• Diseases-causing agents
• Nearly 2,000 different microbes cause diseases in
  the human body
• 10 B infections/year worldwide
• 13 M deaths from infections/year worldwide
  killing about 1/3 of the U.S. population each year

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Impact of Pathogens

• Emerging diseases
• Becoming more prominent over the years
• Zoonosis
• SARS
• Reemerging
• Older diseases increasing in occurrence
• TB
• Malaria
• Hepatitis
• Noninfectious diseases

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Characteristics of Microbes

• Prokaryotic cells
• Smaller
• Lack special structures such as a nucleus and
  organelles
• All prokaryotic cells are microorganisms
• Only some microorganisms are eukaryotic

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Lifestyles of Microorganisms

• Free existence
• Close associations
• Parasites
• hosts

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Antonie van Leeuwenhoek

• First to observe living microbes
• His single-lens magnified up to 300X

(1632-1723)
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Early Medical Microbiology

• Louis Pasteur
• Worked in the wine industry
• Had knowledge about yeast producing alcohol
• Swan-neck flasks
• Tipping the flask would allow the microbes to
  enter the infusion
• Cause them to become cloudy
• Main experiment that helped disprove spontaneous
  generation

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Early Medical Microbiology

• Pasteur discovered that some yeasts made good
  tasting wine
• Mixtures of microbes competed with yeast and made
  wine taste oily or sour
• Developed Pasteurization to deal with this
  problem
• Heated the wine to 56C without oxygen present
  for 30 minutes
• Developed a rabies vaccine

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Early Medical Microbiology

• Robert Koch (120 years ago, German)
• Linked a microscopic organism with a specific
  disease (anthrax)
• Developed method to grow bacteria in pure
  cultures (cultures containing only one kind of
  organism)
• Used solidified gelatin from potato slices mixed
  with agar
• Creates a firm surface that microbes could grow
  on

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Kochs Postulates

• The specific causative agent must be found in
  every case of the disease
• The disease organism must be isolated in pure
  culture
• Inoculation of a sample of the culture into a
  healthy, susceptible animal must produce the same
  disease
• The disease must be covered from the inoculated
  animal

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Early Medical Microbiology

• Oliver Wendell (American physician)
• observed mothers who gave birth at home
  experienced fewer infections than those that gave
  birth in a hospital
• Ignaz Semmelweis (Hungarian doctor)
• showed that women became infected with puerperal
  fever during delivery by doctors coming directly
  from the autopsy room

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Early Medical Microbiology

• Joseph Lister (English surgeon)
• Introduced aseptic techniques
• Aimed at reducing microbes in a medial setting
  and preventing wound infections
• Improved sanitation
• Promotes use of carbolic acid on bandages and
  medical instruments

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Spontaneous Generation Theory

• Germ theory of disease
• Microorganisms can invade other organisms and
  cause disease
• Many diseases are caused by the growth of
  microbes in the body and not by sins, bad
  character, or poverty, etc.
• Spontaneous generation
• Living things arise from nonliving things
• Belief that some forms of life could arise from
  vital forces present in nonliving or decomposing
  matter
• Maggots found in rotting meat arose from a
  nonliving factor
• Microorganisms found in broth that made it cloudy
  appeared from a nonliving factor

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What to expect..

• Different microorganisms
• How to detect microorganisms
• Common disease caused by microorganisms
• How to control the spread of microorganisms
• Immune system