Lecture 7

• Autotrophy


  does not need carbon for energy or structure
• Phototrophy


  (autotroph) uses light
• Lithotrophy


  (autotroph) uses inorganic non-carbonacous material for energy
• Heterotrophy


  uses reduced organic carbon
• Types of heterotrophs

  parasite, pathogen, sprophyte, symbiote bacteria
• Organic trace elements


  essential in synthesis of cofactors

  required for growth, but sufficient amounts in tap water
• Oxygen


  present in many forms

  carbon dioxide, water, oxygen gas

  reactive forms: peroxide radicals, hydroxyl radicals
• Superoxide dismutase


  helps break down toxic radicals of oxygen
• Catalase


  neutralization through decomposition of hydrogen peroxide
• Obligate aerobes


  need oxygen to grow
• Facultative anaerobes


  uses fermentation in absence of oxygen
• Microaerophiles


  grows in small concentrations of molecular oxygen
• Aerotolerant anaerobes


  can survive in oxygen but won't grow
• Obligate anaerobes


  will die from oxygen radicals
• Passive transport 


  high to low concentration gradient (diffusion)
• Active transport 


  requires energy (symport and antiport)
• Symporter


  Active transport

  Two molecules moving in the same direction
• Antiporter


  Active transport

  Two molecules moving in opposite directions
• ATP-binding cassette


  uses energy released by ATP hydrolysis for active transport

  ATP attaches to transporter

  ATP energy changes shape of binding site

  Transporter releases molecule
• PTS system


  Transport of glucose across membrane

  High energy PEP transfer phosphate to glucose (group translocation)
• Phosphate


  limiting nutrient in environment
• Any nutrient


  limiting nutrient in cultures
• Iron


  limiting nutrient in pathogens
• Phosphatase


  enzyme removing a phosphate group from a protein
• Siderophores


  enzyme that scavenges for iron
• Culture

  1. Start with sterile medium, defined or undefined
  2. Media may be solid (add agar or liquid)
  3. Add inoculum, either of pure bacteria or a mixture
  4. Microbes multiply in medium as incubated and results in a culture
• Defined Medium 


  E coli medium

  glucose

  ammonium phosphate, monobasic

  NaCl

  magnesium sulfate, hydrated

  potassium phosphate, dibasic

  water
• Undefined Medium


  nutrient broth

  peptone (protein digest)

  beef extract

  NaCl

  water
• Aerobic growth


  easier

  incubator for constant temperature

  less complicated medium composition
• Anaerobic growth


  airtight chamber or anaerobic hood

  need reducing agent for obligate anaerobes
• Anaerobic jars


  sealed jars with salt packets

  when packet opens, add water

  chemical reaction generates carbon dioxide and hydrogen gas
• Palladium catalyst


  anaerobic jars

  allow reaction of oxygen and hydrogen to form water
• Mycobacterium leprae


  grown in armadillos
• Chlamydiae and rickettsiae

  obligate intracellular bacteria

  grown as parasites in mammalian cell tissue culture
• Capnophiles


  bacteria that desire high carbon dioxide levels
• Isolation

  1. sample is taken from environment
  2. plated onto solid media
  3. isolated colonies are grown
• Agar plates


  will sustain a bacterial culture in the refrigerator for at most 6 months
• Freeze-drying: lyophilization


  freeze at -80C with 15% glycerol to prevent ice crystals from destroying the cells
• Enrichment culture


  isolation technique that makes environment unfavorable for other organisms and very favorable for organism of interest
• Carbon


  Makes up 50% of cell mass

  Derived from inorganic or organic sources