LEC #1

• Microbiology


  An advanced biology course that studies microbes, which are extremely small (microscopic) living organisms and certain non-living entities
• Living microbes


  • Bacteria
  • Archaea
  • Some algae
  • Protozoa
  • Some fungi
• Non-living microbes


  • Viroids
  • Prions
  • Viruses
• Microbes are ubiquitous (i.e., they are found virtually everywhere)
• Microorganisms


  • They are ubiquitous organisms that are too small to be seen by the unaided eye
  • They represent the major fraction of the Earth's biomass
• Pathogens


  Disease-causing microbes
• Nonpathogens


  Microbes that do not cause disease. It is the vast majority of microbes.
• Indigenous microbiota


  Microbes that live on and in our bodies
• Opportunistic pathogens


  Microbes that can cause disease, but usually do not; they can be thought of as microbes that are awaiting the opportunity to cause disease
• Pathogens cause two categories of diseases: infectious diseases and microbial intoxications
• Microbial cells first appeared

  3.8 and 4.3 billion years ago
• For the first 2 billion years of Earth's existence, microorganisms are capable to survive without oxygen in the atmosphere
• Candidates for the first microorganisms on Earth


  • Archaea
  • Cyanobacteria
• Phototrophic microorganisms (organisms that harvest energy from sunlight) occurred


  1 billion years ago
• First phototrophs


  • Purple sulfur bacteria
  • Green sulfur bacteria
• Cyanobacteria (oxygenic phototrophs) evolved and began the slow process of oxygenating Earth's atmosphere, multicellular life forms eventually evolved
• Infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet
• Sumerians and Egyptians produced many foods using fermentation, such as bread, wine, and beer


  Around 5,000 B.C.E.
• During The Dark Ages in Medieval Europe, the pandemic plague has killed as much as one-third of the continent's population in individual pandemics in the Middle Ages
• The plague was caused by Yersinia pestis, a zoonotic disease from domestic and wild rats
• Robert Hooke


  Illustrated the first known image of microscope and fruiting molds, observed the presence of "tiny little boxes" in cork slices, started to formulate the "Cell Theory"
• Theodore Schwann and Matthias Schleiden


  Proposed the Cell Theory in 1838, stating that all plants and animals are made up of cells
• Antoine Van Leeuwenhoek


  "Father of Microbiology", made many simple single-lens microscopes and observed "animalcules" (bacteria and protozoa)
• Spontaneous generation


  The theory that living creatures could arise from nonliving matter and that such processes were commonplace and regular
• Francesco Redi


  Italian physician who first challenged and disproved the theory of spontaneous generation in 1668 through a controlled experiment
• John Needham


  Defended the theory of spontaneous generation after observing that a heated uncovered flask containing broth still developed microorganisms after cooling the broth in open air
• Lazzaro Spallanzani


  Italian Catholic priest who disproven Needham's claim by suggesting that microorganisms from the air probably entered Needham's solutions after they were boiled
• Rudolf Virchow


  Famous German physician and cellular pathologist who introduced the theory of biogenesis in 1858, claiming that living cells arise only from preexisting living cells
• Louis Pasteur


  French chemist who resolved the debate over spontaneous generation in 1861 through his experiment with boiled broth in flasks with S-shaped necks
• Edward Jenner


  Young British physician who pioneered the concept of vaccination by inoculating a healthy 8-year-old boy with scrapings of cowpox blisters
• Ignaz Sammelweiz


  Hungarian physician who pioneered the antiseptic procedures through the development of the proper handwashing technique, lowering the death rate of newly delivered mothers
• Other contributions of Pasteur

  • Investigated different fermentation products
  • Developed the pasteurization process
  • Discovered life forms that could exist without oxygen (anaerobes)
  • Developed several vaccines, including rabies and anthrax vaccines
• Joseph Lister


  British surgeon and medical scientist who introduced the aseptic technique in order to kill and prevent from microbial infection of surgical patients
• Robert Koch


  Discovered that Bacillus anthracis produced spores, developed methods of fixing and staining bacteria, developed methods to cultivate bacteria, made significant contributions to the germ theory of disease, developed Koch's Postulates
• Circumstances do exist in which Koch's Postulates cannot be fulfilled (e.g. viruses, Mycobacterium tuberculosis, Treponema pallidum)

  
• Hans Christian Joachim Gram


  Developed Gram staining technique - a useful technique in classifying bacteria through the thickness of their cell walls
• Richard Petri


  Developed a transparent double-sided dish known as "Petri dish", a standard tool for obtaining pure cultures
• Paul Ehrlich


  Proposed the theory of immunity in 1890 and developed salvarsan - a drug that can treat syphilis in 1910
• Sergei Winogradsky


  Isolated and characterized nitrogen and sulfur-fixing bacteria from soil sediments in the mid to late 1800s
• Alexander Fleming


  Accidentally discovered the first antibiotic drug, penicillin, from Penicillium chrysogenum in 1928