1. Microbiology Lec

• Microbiology


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

  • Bacteria
  • Archaea
  • Some algae
  • Protozoa
  • Some fungi
• Non-living microbes (acellular microbes or infectious particles)

  • Viroids
  • Prions
  • Viruses
• Microbes are ubiquitous (found virtually everywhere)
• Pathogens


  Disease-causing microbes
• Non-pathogens


  Microbes that do not cause disease (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 are awaiting the opportunity to cause disease
• Categories of diseases caused by pathogens

  • Infectious diseases
  • Microbial intoxications
• Fossils of primitive microorganisms date back about 3.5 billion years
• Candidates for the first microorganisms on Earth are archaea and cyanobacteria
• Infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet
• Earliest known account of pestilence occurred in Egypt in about 3180 BCE
• Anton van Leeuwenhoek


  The "Father of Microbiology", not a trained scientist, 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
• Francisco Redi's experiment


  Disproved the theory of spontaneous generation
• Louis Pasteur's experiment


  Further disproved the theory of spontaneous generation
• 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, developing methods of fixing and staining bacteria, and developing methods to cultivate bacteria
• Koch's Postulates


  • A particular microbe must be found in all cases of the disease and must not be present in healthy animals or humans.
  • The microbe must be isolated from the diseased animal or human and grown in pure culture in the laboratory.
  • The same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible laboratory animals.
  • 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
• Reasons to study microbiology

  • Microbes 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
  • Microorganisms are involved in the decomposition of dead organisms and waste products
  • Saprophytes live on dead and/or decaying organic matter
  • Bioremediation uses microbes to clean up toxic wastes and other industrial waste products
  • Microbes play essential roles in various elemental cycles
  • Algae and bacteria serve as food for tiny animals and are important links in food chains
  • Microbes that live in the intestinal tracts of animals aid in the digestion of food and produce beneficial substances
  • Microbes have been used as "cell models" to learn about cells in general
  • Microbes are used in many industries, such as food, beverage, chemical, and antibiotic industries and in genetic engineering
• Biotechnology


  The use of living organisms or their derivatives to make or modify useful products or processes
• Career fields within microbiology

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


  Involves the study of pathogens, the diseases they cause, and the body's defenses against disease; concerned with epidemiology, transmission of pathogens, disease-prevention measures, aseptic techniques, treatment of infectious diseases, immunology, and production of vaccines
• Metric system units used to express microbe sizes


  Meter (m), micrometer (μm), nanometer (nm)
• A typical spherical bacterium (coccus) is approximately 1 μm in diameter
• A typical rod-shaped bacterium (bacillus) is approximately 1 μm wide and 3 μm long
• Most viruses that cause human diseases range in size from 10 to 300 nm

  
• Ebola viruses can be as long as 1,000 nm (1 μm)
• Resolving power or resolution


  The limit as to what can be seen using an optical instrument
• Simple microscope


  Contains only one magnifying lens, such as a magnifying glass
• Compound microscope


  Contains more than one magnifying lens, also referred to as a compound light microscope
• Compound light microscopes usually magnify objects about 1,000 times
• The resolving power of a compound light microscope is approximately 0.2 μm (about 1,000 times better than the resolving power of the unaided human eye)
• Objects cannot be seen if they are smaller than half of the wavelength of visible light
• Ocular lens


  The eyepiece lens in a compound microscope