Microbiology

• Leeuwenhoek's observations


  Introduced most types of microorganisms to the world
• Linnaeus


  Classified Leeuwenhoek's discoveries in his taxonomic system
• Microorganisms


  • Bacteria
  • Archaea
  • Fungi
  • Protozoa
  • Algae
  • Small multicellular animals
• Bacteria and archaea


  • Prokaryotic (lack nuclei)
  • Bacterial cell walls composed of peptidoglycan
  • Archaea lack peptidoglycan cell walls
• Bacteria and archaea


  • Reproduce asexually
  • Most are much smaller than eukaryotic cells
  • Live singly, in pairs, chains or clusters
  • Found in almost every habitat with sufficient moisture
• Archaea are often found in extreme environments
• No archaea are known to cause diseases in humans
• Bacteria are beneficial in many ways, including degrading dead organisms to release nutrients
• Fungi


  • Eukaryotic (have nuclei)
  • Obtain food from other organisms (not photosynthetic)
  • Have cell walls
• Viruses are not considered "organisms" because they cannot carry on the chemical reactions of living things
• Protozoa


  Single-celled eukaryotes, some cause disease
• Algae


  Eukaryotic, important providers of oxygen, food for marine animals, and chemicals used in growth media
• Parasitic worms


  Largest organisms studied by microbiologists, often visible without a microscope, but have microscopic immature stages
• Viruses are the smallest microbes, only visible with an electron microscope
• Golden Age of Microbiology

  Includes the men who proposed or refuted the theory of spontaneous generation, and the development of the scientific method
• Pasteur


  The Father of Microbiology
• Pasteur and Buchner's study of fermentation

  1. Led to discovery of anaerobic bacteria

  2. Established fields of industrial microbiology (biotechnology) and biochemistry

  3. Enabled study of metabolism
• Germ theory of disease


  Pathogens cause infectious diseases
• Etiology


  The study of the causation of diseases
• Koch's postulates


  Logical steps to prove the cause of an infectious disease
• Gram stain


  Procedure developed in 1880s to differentiate bacteria into Gram positive and Gram negative
• Infection control


  Includes control of healthcare-associated infections (HAI) or nosocomial infections, and epidemiology
• Immunology


  Field begun by Jenner's cowpox vaccine for smallpox, advanced by Pasteur
• Chemotherapy


  Field begun by Ehrlich's search for "magic bullets" to kill microorganisms
• Modern microbiology focuses on biochemistry, microbial genetics, and molecular biology
• Knowledge from basic research has been applied to recombinant DNA technology and gene therapy
• Environmental microbiology


  The study of microorganisms in their natural environment
• Serology


  The discovery of chemicals in the blood active against specific pathogens
• Advancements in chemotherapy in the 1900s included the discovery of penicillin and sulfa drugs
• Smallpox was likely the worst infectious disease of all time, killing an estimated 300 million people in the 9th century
• Smallpox vaccination


  Invented by Edward Jenner, the world's first immunization
• Smallpox was eradicated worldwide, with the last case documented in 1977
• Smallpox virus still exists, kept frozen in secure laboratories
• Science proceeds by posing questions about observations
• Early written records show people have always asked questions about the natural world
• The invention of the microscope about 350 years ago began providing clues to answer fundamental questions about life
• Bacteria have a poor reputation in our world, but the great majority do not cause disease in animals, humans, or crops. Indeed, bacteria are beneficial to us in many ways.
• Without beneficial bacteria, our bodies would be much more susceptible to disease.
• Bacteria (and fungi) degrade dead plants and animals to release phosphorus, sulfur, nitrogen, and carbon back into the air, soil, and water to be used by new generations of organisms.
• Without microbial recyclers, the world would be buried under the corpses of uncountable dead organisms.