LLL

• Impacts of microbial metabolism

  • Disease and food spoilage
  • Nitrogen cycle
  • Beverages and food
  • Sewage treatment
  • Drugs
• Carbohydrate catabolism

  • Respiration - glycolysis, Krebs cycle, electron transport chain
• Respiration


  Generates 38 ATPs from 1 glucose molecule
• Fermentation


  Produces 2 ATPs from 1 glucose molecule, does not require Krebs cycle or ETC
• Important processes


  • Lipid catabolism - lipases break down lipids
  • Protein catabolism - proteases and peptidases break down proteins
• Metabolic Diversity


  • Phototrophs - use light as energy source
  • Chemotrophs - use redox of inorganic/organic compounds
  • Autotrophs - self-feeders
  • Heterotrophs - feed on others
  • Chemoheterotrophs - most medically important organisms
• Physical Requirements


  • Temperature - psychrophiles, mesophiles, thermophiles
  • pH - most bacteria grow best between 6.5-7.5
  • Osmotic pressure - adaptations like extreme halophiles
• Chemical Requirements


  • Carbon
  • Nitrogen
  • Sulfur
  • Phosphorus
  • Trace elements
  • Organic growth factors
• Chemical Requirements


  • Oxygen - obligate aerobes, facultative anaerobes, obligate anaerobes, aerotolerant anaerobes, microaerophiles
• Culture Media


  Nutrient material prepared for the growth of microorganisms
• Inoculum


  Microbes that are introduced into a culture medium to initiate growth
• Culture


  Microbes that grow and multiply in a culture medium
• Culture media must be initially sterile
• Forms of Culture Media

  • Broth - liquid
  • Slants - tubes held at an angle
  • Stab tubes / deeps - bacteria inoculated by stabbing
  • Plates - Petri dishes
• Colony forms


  • Mannitol salt agar - differential and selective
  • MacConkey agar - differentiates lactose fermenters and non-fermenters
• Streak plate method


  Most commonly used method for obtaining pure cultures
• Preservation


  • Refrigeration for short-term
  • Deep-freezing
  • Lyophilization (freeze-drying)
• Five "I"s of Culturing Microbes

  • Inoculation
  • Isolation
  • Incubation
  • Inspection
  • Identification
• Binary fission


  Most common mode of microbial reproduction
• Budding


  Another mode of microbial reproduction
• Sterilization and Anti-Microbial Methods

  • Sterilization
  • Disinfection
  • Antisepsis
  • Sanitization
• Aseptic Technique


  Process to prevent contamination of cultures, yourself, and the environment
• Control of Growth


  • Moist heat - autoclaving, pasteurization
  • Dry heat - direct, incineration, hot-air
  • Filtration
  • Refrigeration
  • Deep-freezing and freeze-drying
  • High pressure
  • Desiccation
  • Osmotic pressure
  • Radiation
• Disinfectants


  • Phenols and phenolics - Triclosan
  • Biguanides - chlorhexidine
  • Halogens - chlorine
  • Alcohols
  • Heavy metals
  • Surface-active agents
  • Aldehydes
  • Peroxygens and other oxygen forms