Microbiology

• Microbiology involves the study of organisms too small to be seen without magnification
• Microorganisms included in microbiology are:

  • Bacteria
  • Archaea
  • Viruses
  • Fungi
  • Protozoa
  • Helminths (worms)
  • Algae
• Microbes help by:

  • Decomposing organic waste
  • Performing photosynthesis
  • Producing ethanol, acetone, vinegar, cheese, bread, insulin, and drugs
• Microbes harm by:

  • Causing disease
  • Causing food spoilage
• Branches of Microbiology include:

  • Bacteriology (study of bacteria)
  • Mycology (study of fungi)
  • Protozoology (study of protozoa)
  • Virology (study of viruses)
  • Parasitology (study of parasites)
  • Phycology or Algology (study of algae)
• Microbial Genetics involves the function of genetic material and biochemical reactions that make up a cell’s metabolism
• Microbial Ecology studies the interrelationships between microbes and the environment, including their roles in nutrient cycles and natural ecosystems
• Origins of Microorganisms:

  • Bacteria-like organisms have existed on earth for about 3.5 billion years
  • Prokaryotes are simple cells, while eukaryotes are complex cells
• Microbial Structure:

  • Prokaryotes are microscopic, unicellular organisms that lack nuclei and membrane-bound organelles
  • Eukaryotes can be unicellular or multicellular, with nuclei and membrane-bound organelles
  • Viruses are acellular, parasitic particles composed of nucleic acid and protein
• Types of Microorganisms:

  • Bacteria
  • Archaea
  • Viruses
  • Fungi
  • Protozoa
  • Helminths (worms)
  • Algae
• Bacteria:

  • Prokaryotic
  • Have peptidoglycan cell walls
  • Reproduce by binary fission
  • Gain energy from organic chemicals, inorganic chemicals, or photosynthesis
• Archaea:

  • Prokaryotic
  • Lack peptidoglycan
  • Live in extreme environments like methanogens, extreme halophiles, and extreme thermophiles
• Viruses:

  • Acellular
  • Contain DNA or RNA in a core surrounded by a protein coat
  • Replicate only within a living host cell
• Fungi:

  • Eukaryotic
  • Have chitin cell walls
  • Use organic chemicals for energy
  • Molds and mushrooms are multicellular, while yeasts are unicellular
• Protozoa:

  • Eukaryotes
  • Absorb or ingest organic chemicals
  • May be motile via pseudopods, cilia, or flagella
• Helminths:

  • Eukaryotes
  • Parasitic flatworms and roundworms
  • Have microscopic stages in life cycles
• Algae:

  • Unicellular or multicellular
  • Widespread inhabitants of fresh and marine waters
  • Vary in length from a few micrometers to 100 meters
• Taxonomy involves organizing, classifying, and naming living things
• Levels of Classification:

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• History of Microbiology:

  • Microbiology dates back to the first people who used simple microscopes to observe small living things
  • Robert Hooke and Anton van Leeuwenhoek made significant contributions
• Debate over Spontaneous Generation:

  • Spontaneous Generation was the belief that some forms of life could arise from nonliving matter
  • Louis Pasteur disproved spontaneous generation and supported the Theory of Biogenesis
• Experiments on Spontaneous Generation:

  • Francesco Redi's experiment with flies and meat
  • John Needham's experiment with broth
  • Lazzaro Spallanzani's experiment with soups
• In 1864, Louis Pasteur published the results of an experiment that disproved spontaneous generation in microscopic organisms
• Pasteur's experiment involved special S-shaped flasks filled with broth, which were boiled, placed at various locations, and observed for microbial growth
• Pasteur's S-shaped flask experiment demonstrated the theory of biogenesis, showing that microbes only come from other microbes (life from life)