Chapter 1

• Microbiology


  An advanced biology course that is the study of microbes, which are extremely small (microscopic) living organisms and certain nonliving entities
• Living microbes (cellular microbes or microorganisms)

  • Bacteria
  • Archaea
  • Some algae
  • Protozoa
  • Some fungi
• Nonliving microbes (acellular microbes or infectious particles)

  • Viroids
  • Prions
  • Viruses
• Pathogens


  Disease-causing microbes
• Nonpathogens


  Microbes that do not cause disease
• Indigenous microbiota


  Microbes that live on and in our bodies
• Opportunistic pathogens


  Microbes that can cause disease, but usually do not
• Categories of diseases caused by pathogens

  • Infectious diseases
  • Microbial intoxications
• Microbes


  • They play significant roles in our lives and are essential for life on this planet
  • Photosynthetic algae and bacteria produce much of the oxygen in our atmosphere
  • They are involved in the decomposition of dead organisms and waste products
  • They play essential roles in various elemental cycles
  • They serve as food for tiny animals and are important links in food chains
  • They aid in the digestion of food and produce beneficial substances
  • They are used in many industries and in genetic engineering
• Fossils of primitive microorganisms date back about 3.5 billion years
• Candidates for the first microorganisms on Earth are archaea and cyanobacteria
• Earliest known account of pestilence occurred in Egypt


  About 3180 BC
• Anton van Leeuwenhoek


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


  French chemist who made numerous contributions to microbiology, including investigating different fermentation products, developing the pasteurization process, discovering life forms that could exist without oxygen (anaerobes), and developing several vaccines
• Robert Koch


  German physician who made numerous contributions to microbiology, including making significant contributions to the germ theory of disease, discovering that Bacillus anthracis produced spores, and developing methods of fixing, staining, and cultivating bacteria
• Koch's Postulates


  1. A particular microbe must be found in all cases of the disease and must not be present in healthy animals or humans

  2. The microbe must be isolated from the diseased animal or human and grown in pure culture in the laboratory

  3. The same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible laboratory animals

  4. The same microbe must be recovered from the experimentally infected animals and grown again in pure culture
• If an organism fulfills Koch's Postulates, it has been proven to be the cause of that particular infectious disease
• Koch's Postulates helped prove the germ theory of disease
• Koch gave a tremendous boost to the development of microbiology by stressing laboratory culture and identification of microorganisms
• Circumstances do exist in which Koch's Postulates cannot be fulfilled
• Microbiologist


  A scientist who studies microbes
• Career fields within the science of microbiology

  • Bacteriology
  • Phycology
  • Protozoology
  • Mycology
  • Parasitology
  • Virology
• Medical microbiology


  Involves the study of pathogens, the disease they cause, and the body's defenses against disease, and is concerned with epidemiology, transmission of pathogens, disease-prevention measures, aseptic techniques, treatment of infectious diseases, immunology, and production of vaccines
• Microbes are found everywhere, including soil, water, air, plants, animals, and humans.
• Virus particles (virions) consist mostly of protein and nucleic acid, either DNA or RNA.
• Bacteria are single-celled prokaryotic organisms with cell walls made of peptidoglycan.