Introductory Microbiology

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Introductory Microbiology

• Dr. Heather Townsend

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Characteristics of Life

• Growth and development
• Reproduction and heredity
• Metabolism
• Movement and/or irritability
• Cell support, protection, and storage mechanisms
• Transport of nutrients and waste
• Living things are made of cells!!

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All cells.

• Have an outer plasma membrane
• Contain DNA
• Enclosed within the cell somewhere
• Contain cytoplasm
• Everything between the plasma membrane and the
  region of DNA
• Gives cells their shape
• Assist in movement of cell and organelles

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Characteristics of Microbes

• Prokaryotic cells
• Smaller
• Lack special structures such as a nucleus and
  organelles
• All prokaryotic cells are microorganisms
• Some microorganisms are eukaryotic
• Viruses?

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Microorganisms
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Characteristics of Cells

• Eukaryotic cells
• Animals, plants, fungi, and protists
• contain double-membrane bound nucleus with DNA
• contain membrane-bound organelles
• 10100 µm in diameter

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Characteristics of Cells

• Prokaryotic cells
• 1.0 µm in diameter
• Bacteria and archaea
• no nucleus
• no membrane-bound organelles

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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

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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

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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. Helminths
• Large, multicellular
• Parasitize host tissues
• Organs for reproduction, digestion, movement,
  protection
• Mouthparts
• Ingestion of larvae or eggs in food

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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General cell characteristics

• Locomotor appendages
• External boundaries

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External Structures of Cells

• Locomotor appendages
• flagella
• long, sheathed cylinder containing microtubules
• covered by an extension of the cell membrane
• function in motility
• cilia
• similar in overall structure to flagella
• shorter and more numerous
• found only on a single group of protozoa and
  certain animal cells
• function in motility, feeding and filtering

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External Boundary Structures

• Plasma (cell) membrane
• typical bilayer of phospholipids and proteins
• serves as selectively permeable barrier in
  transport

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External Structures of Cells

• Glycocalyx
• an outermost boundary that comes into direct
  contact with environment
• usually composed of polysaccharides
• appears as a network of fibers, a slime layer or
  a capsule
• functions in adherence, protection, and signal
  reception
• Beneath the glycocalyx
• Fungi and most algae - cell wall
• Protozoa, a few algae, and all animal cells
  cell membrane

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External Boundary Structures

• Cell wall
• Fungi
• thick inner layer of polysaccharide fibers
• composed of chitin or cellulose and a thin layer
  of mixed glycans
• Algae
• varies in chemical composition
• substances include cellulose, pectin, mannans,
  silicon dioxide, and calcium carbonate
• Bacteria!!!
• Dependent on cell wall composition

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Prokaryote
Eukaryote
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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

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Historical Microbiology

• 1546 physician suggest that invisible organisms
  may be involved with disease
• Abiogenesis vs biogenesis

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Early Microbiologists

• Antonie van Leeuwenhoek
• 1676
• First to observe living microbes
• His single-lens magnified up to 300X

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Early Medical Microbiology

• Francesco Redi
• 1688
• 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
• Debate over spontaneous generation led in part to
  development of scientific method

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Science

• Scientific method
• 1. Observe some aspect of the natural world and
  ask questions about it
• 2. Hypothesis
• 3. Make predictions
• 4. Test the predictions
• 5. Repeat the tests or develop new ones
• 6. Analyze and report the test results and
  conclusions

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Early Medical Microbiology

• Oliver Wendell (American physician) 1837
• observed mothers who gave birth at home
  experienced fewer infections than those that gave
  birth in a hospital
• Ignaz Semmelweis (Hungarian doctor) 1850
• 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

• Louis Pasteur - 1861
• 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
• Developed Pasteurization
• Developed a rabies vaccine

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Early Medical Microbiology

• Joseph Lister (English surgeon) 1865
• 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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Early Medical Microbiology

• Robert Koch (German) 1871
• 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

1. The specific causative agent must be found in
   every case of the disease
2. The disease organism must be isolated in pure
   culture
3. Inoculation of a sample of the culture into a
   healthy, susceptible animal must produce the same
   disease
4. The disease must be recovered from the inoculated
   animal

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germ theory of disease

• pathogenic theory of medicine
• Proposes that microorganisms are the cause of
  many diseases
• Controversial, but validated in late 19th century

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1900s and beyond..

• Paul Ehrlich 1900
• First to use dyes to ID bacteria
• Named concept of chemotherapy
• Treatment for syphilis
• magic bullet
• Compound could be made to selectively target a
  disease-causing organism

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1900s and beyond

• Alexander Fleming 1929
• observed that a species of Penicillium mold
  killed bacterial cells
• led to the development of penicillin
• Two types of cells recognized!!!

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MicrobiologyNow

• Microbiology continues to face many challenges
• A pathogen can cause more than one disease
• Pathogens are becoming resistant to
  antimicrobials
• Pathogens can be used intentionally to infect
  large numbers of people through bioterrorism

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Microscopy

• Micrometer Size Range
• Most bacterial and archaeal cells are 1-5
  micrometers (µm) in length

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How to view microbes?

• Light Microscopy
• Visible light passes through multiple lenses and
  through the specimen
• Light microscopes usually have at least 3 lenses
• Scanning (4X)
• low-power (10X)
• high-power (45X)
• oil-immersion (100X)

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How to view microbes?

• Staining techniques
• simple stain technique
• negative stain technique
• Special stains

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Taxonomy

• Organizing, classifying and naming living things
• In the mid-1700s, Carolus Linnaeus published
  Systema Naturae, establishing a uniform system
  for naming organisms
• Nomenclature gives scientific names to organisms
• Identifying and classifying organisms according
  to specific criteria

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Taxonomy

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• species

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3 Domains

• Eubacteria
• true bacteria
• peptidoglycan
• Archaea
• odd bacteria that live in extreme environments
• high salt, heat, etc. (usually called
  extremophiles)
• Eukarya
• have a nucleus organelles
• Protista
• Algae
• Fungi
• Plantae
• Animalia

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Naming Most Micoorganisms

• Binomial (scientific) nomenclature
• Gives each microbe 2 names
• Genus - noun, always capitalized
• species - adjective, lowercase
• Both italicized or underlined
• Staphylococcus aureus (S. aureus)
• Bacillus subtilis (B. subtilis)
• Escherichia coli (E. coli)

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Microorganisms in history.

• Edward Jenner
• Smallpox vaccine
• Tested it on his son and neighborhood children
• Japan
• Plague infected fleas covered with cholera
• Tuskegee Syphilis experiment
• 1932 - 1972
• Guatemala's National Mental Health Hospital -
  1946
• US Infected patients with syphilis
• Vector - prostitutes

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Microorganisms in history

• University of PA 1950
• Infected 200 female prisoners with hepatitis
• Biological warfare
• CIA whooping cough in FL 12 killed
• US Army mosquitoes in South
• Plum Island, NY
• Lyme Disease??

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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