Microb lec1

• Microbiology


  The study of microbes/microorganisms
• Microorganisms


  • Viruses
  • Bacteria
  • Fungi
  • Protozoa
  • Cyanobacteria (Blue-green algae)
• Bacteria


  • Staphylococcus
  • Streptococcus
  • Mycobacterium
• Microorganisms are found everywhere in our environment
• Majority of microbes do not cause disease
• Pathogens


  Disease causing microbes
• Commensals


  Non disease causing microorganisms
• Opportunists


  Most microorganisms are opportunists
• Branches of Microbiology


  • Medical Microbiology
  • Food Microbiology
  • Agricultural Microbiology
  • Applied Microbiology
• Medical Microbiology


  Deals mainly with diseases
• Food Microbiology


  • Microbes as food
  • Microbes in food production
  • Food processing
• Agricultural Microbiology


  • Viral, bacterial and fungal diseases of animals and crop plants
  • Beneficial symbiosis
  • Composting, ensilaging, biological control, genetic engineering
• Applied Microbiology


  • Sewage disposal, oil spill clean ups
  • Methanogenesis
  • Pesticide breakdown
  • Microbial fertilizers, water supply industry, single cell protein, fine chemicals, antibiotics, vitamins, alcohol, flavorings, enzymes, quality control, basis of biotechnology
  • Recycling of nutrients
• Robert Hooke observed sliver of cork and coined the term cell

  Mid-1600s
• Antonie van Leeuwenhoek, 'The father of Microbiology', described microbes


  1670s
• van Leeuwenhoek was a true scientist and chronicled his observations
• Louis Pasteur showed that tiny organisms were found in wine and were responsible for fermentation


  1800s
• Pasteur's grape juice went sour on standing for sometime, but remained the same when heated and bottled tightly closed</b>
• Certain microbes in the air were responsible for the spoilage
• Pasteur's breakthrough was the development of the Koch's postulates (1881)
• Germ theory of disease


  Microorganisms play significant roles in the development of infectious disease
• Koch's Postulates


  Rules-of-proof of causality for infectious disease
• Certain microbes in the air are responsible for the spoilage of food
• Breakthroughs in microbiology with the development of Koch's postulates

  1881
• Louis Pasteur conducted experiments to investigate the role of microorganisms in spoilage
• Louis Pasteur modified the experiment using swan-necked flasks
• Reasoning behind the germ theory of disease

  1. Microbes could be transmitted to humans

  2. This led Pasteur to propose the germ theory of disease, which states that microorganisms play significant roles in the development of infectious disease

  3. Diseased tissues often yield more than one microbe

  4. Consequently, not always obvious which microbe is the cause of disease

  5. Big problem in medical science in the 19th century
• Koch's Postulates


  1. The organism in question must always be found associated with a particular disease

  2. The organism must be isolated and grown in pure culture

  3. The organism grown in pure culture must be inoculated into a healthy host under favorable conditions and induce a characteristic disease

  4. The organism must be re-isolated from the second host and compared with the first culture

  5. Both the diseased condition produced by inoculation and the organisms recovered from the inoculated host must correspond to the original diseased condition and to the first organisms isolated, respectively
• A schematic diagram of Koch's postulate is provided
• Prokaryotic cells (bacteria) and eukaryotic cells (plant and animal) differ in several ways
• Differences between prokaryotic and eukaryotic cells

  • Cell size
  • Nuclear membrane
  • Number of chromosomes
  • Mitosis
  • Organelles
  • Endoplasmic reticulum
  • Cell wall
  • Cytoplasmic Ribosomes
  • Organelle Ribosomes
  • Cilia
  • Flagella
• Prokaryotic diversity


  • Differentiated mainly by their different morphological, physiological, and behavioral characteristics
  • Morphology (Shape/arrangements)
  • Chemical composition (staining reactions)
  • Nutritional requirements
  • Biochemical activities and some sources of energy (sunlight and chemicals)
• Three major forms of bacteria

  • Spherical or round forms (Cocci)
  • Rod-shaped forms (Bacilli)
  • Spiral forms or Spirillum/twisted-like corkscrew
• Monomorphic


  Bacteria that maintain a single shape
• Pleomorphic


  Bacteria that can have many shapes
• Arrangements of cocci after cell division

  • Diplococcus/Diplococci
  • Streptococcus/Streptococci
  • Tetrads
  • Sarcina
  • Staphylococci
• Arrangements of bacilli after cell division

  • Single rods
  • Diplobacilli
  • Streptobacilli
• Diagrams showing the various forms and arrangements of bacteria are provided
• Typical bacterial cell structure includes appendages, surface layers, cytoplasm, and special structures
• Features or structures outside of the bacterial cell

  • Glycocalyx (Capsule)
  • Flagellum/Flagella
  • Axial Filaments
  • Fimbriae and Pili