MicroPara

• Physiology


  The scientific study of functions and mechanism in a living system
• Microbial Physiology


  Concerns the vital life processes of microorganism
• Microbial Physiology includes


  • Nutrition (nutritional requirements)
  • Environmental factors affecting survival of bacteria
  • Growth and multiplication
  • Metabolism
• Bacterial growth


  Increase in size and number of cells
• Bacterial cell division


  Binary fusion (exact copy of itself)
• Basic requirements for bacterial growth

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Inorganic salts
• Different Types of Heterotrophic Bacteria

  • Parasitic (derive food from living organisms)
  • Saprophytic / saprophytes (feed on dead and decaying organic matter)
  • Symbiotic (live in symbiotic association with other organism)
• Autotrophs


  Bacteria which can synthesize their own food
• Heterotrophs


  Bacteria which cannot synthesize their own food
• How Autotrophs Produce their Own Food

  1. Photosynthesis (use of light)

  2. Chloroplast (allows production of nutrients from light)

  3. Raw materials (carbon dioxide and water)

  4. Produce nutrients (glucose and oxygen)
• Chemosynthesis


  Uses chemicals such as CH4, or H2S and along with O2 to produce CO2 and energy (Oxidation)
• Categorizing Microorganisms According to their Energy and Carbon Sources

  • Phototrophs (use light)
  • Chemotrophs (use either inorganic or organic chemicals)
  • Chemolithotrophs (use inorganic chemicals)
  • Chemoorganotrophs (use organic chemicals)

  
• Autotrophs


  • Photoautotroph (use light's energy and CO2)
  • Photoheterotrophs (use light and organic compounds)
• Heterotrophs


  • Chemoautotrophs (use chemical as energy source and CO2 as carbon source)
  • Chemoheterotrophs (use chemicals as energy source and organic compound as carbon source)
• Examples of Nutritional Types

  • Photoautotroph (oxygenic: cyanobacteria, algae, plants; anoxygenic: green, purple bacteria)
  • Photoheterotroph (green, purple nonsulfur bacteria)
  • Chemoautotroph (hydrogen, iron, sulfur, nitrogen and carbon monoxide-oxidizing bacteria)
  • Chemoheterotroph (fermentative bacteria, animals, protozoa, fungi, bacteria)

  
• Requirements for Growth


  • Physical Requirements (temperature, pH, osmotic pressure)
  • Chemical Requirements (carbon, N, S, P, trace elements, O2, organic growth factors)
• Thermophiles


  Bacteria which grow in hot environments
• Psychrophiles / Cryophiles


  Bacteria which grow in cold environments
• Mesophiles


  Bacteria which grow in normal temperatures

  
• Acidophiles


  Organisms that live in acidic environments
• Alkaliphiles


  Organisms that live in basic environments
• Hypertonic


  High solute - low solvent, cell will shrink
• Hypotonic


  Low solute - high solvent, cell will swell and burst (cell lysis)
• Isotonic


  Equal number of solute and solvent
• Essential Elements


  • C, H, O, N, P, S (carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur)
• Mineral Sources


  • Na, K, Mg, Fe, Mn, Ca, Co, etc.
• Organic Growth Factors


  Required by bacteria for their growth and maintenance - called BACTERIAL VITAMINS
• Environmental Factors Affecting Growth

  • Water
  • Oxygen
  • Carbon dioxide
  • Temperature
  • Hydrogen Ion Concentration
  • Light
  • Osmotic pressure
  • Symbiosis and Antagonism
• Water


  80% of bacterial cell consist of water, dehydration is detrimental for most bacteria
• Spores


  Resistant to dessication and may survive in the dry state for several decades (preservation)
• Freeze Drying or Lyophilization


  Drying in vacuum in cold, method of preservation of bacteria, viruses and many labile biological materials
• Oxygen Requirements


  • Aerobe (require oxygen for growth)
  • Anaerobes (do not require oxygen for growth)
  • Obligate Aerobe (grow only in presence of oxygen)
  • Obligate Anaerobes (strictly grow in absence of oxygen)
  • Facultative Anaerobe (aerobes but can grow with lack of oxygen or in absence of oxygen)
  • Microaerophilic (grow with trace amount of oxygen)
  • Aerotolerant Anaerobes (anaerobes which do not require oxygen but tolerate presence of oxygen)
• Carbon Dioxide


  Provided by cellular metabolism and from environment, some fastidious organisms may require additional CO2 from exogenous sources
• Capnophilic


  Requiring excess amount of CO2
• Temperature Requirements


  • Minimum Growth Temperature (lowest temperature organism can survive and replicate)
  • Optimum Growth Temperature (temperature organism grows best and healthiest)
  • Maximum Growth Temperature (highest temperature growth can occur)
  • Thermal Death Point (lowest temperature all microbes are killed in 10-minute exposure)

  
• Psychrophiles


  Bacteria which grow below 20°C (cold temperature)
• Mesophiles


  Bacteria which grow between 20-40°C (moderate temperature)
• Thermophiles


  Bacteria which grow at higher temperature i.e. 60-80°C

  
• Acidophilic


  Bacteria grow in acidic pH
• Alkaliphiles


  Bacteria grow in alkaline pH