bacterial nutrition

• Nutrition


  The kind of food used and the methods by which it is assimilated and utilized
• Purposes of Nutrition

  • To synthesize protoplasm
  • To supply energy for all life processes
• Nutrients


  Substances that provide nourishment, e.g. the minerals that a plant takes from the soil or the constituents in food that keep a human body healthy and help it to grow
• Carbon Source

  Nonmetallic chemical element - source for the synthesis of the protoplasm of bacteria. Sources: wood, asphalt, gasoline or carbon dioxide in the air
• Autotrophs

  Require only carbon dioxide, able to manufacture nutrients
• Heterotrophs

  Require an organic form of carbon, getting nutrients through food digestion
• Lithotrophs

  Use inorganic compounds
• Classification of bacteria by Carbon Source

  • Autotrophs
  • Heterotrophs
  • Lithotrophs
• Nitrogen Source


  Some bacteria use atmospheric oxygen, some thrive on inorganic nitrogen compounds and others derive their nitrogen from proteins or any naturally occurring organic nitrogen compounds
• Minerals required

  • Sulphur
  • Phosphates
  • Magnesium
  • Iron
  • Sodium
  • Potassium
  • Manganese
  • Zinc
  • Copper
  • Cobalt
• Growth Factors

  Vitamins and amino acids
• Temperature


  Major environmental factor controlling microbial growth
• Cardinal Temperatures

  • Minimum
  • Optimum
  • Maximum
• Psychrophiles or Cryophiles

  Cold loving, grow at 0 - 20 °C or less
• Mesophiles

  Moderate loving, grow at 20°C - 45°C
• Thermophiles

  Heat loving, grow between 50°C-60°C
• Hyperthermophiles


  Grow at optima greater than 80°C
• Facultative or Eurithermophiles


  Thermophilic bacteria that extends into the mesophilic region
• Stenothermophiles


  Thermophilic bacteria that grows above 60°C
• Aerobes


  Grow in the presence of free oxygen
• Anaerobes


  Grow in the absence of free oxygen
• Facultatively anaerobes


  Grow in either the absence or the presence of free oxygen
• Microaerophiles


  Grow in the presence of minute quantities of oxygen
• Capnophiles


  Bacteria that requires 5-10% carbon dioxide for their growth
• pH


  The degree of acidity or alkalinity
• Acidophiles


  Organisms that grow best at low pH
• Alkaliphiles


  Organisms that grow best at high pH
• Neutrophiles


  Most pathogenic bacteria
• Photosynthetic Autotrophs


  Requires light as the source of energy
• Osmophilic bacteria


  Requires high osmotic pressure
• Halophilic Bacteria


  Requires high concentration of salt
• Osmotic pressure

  Depends on the surrounding solute concentration and water availability
• Water activity (aw)


  The ratio of the vapor pressure of the air in equilibrium with a substance or solution to the vapor pressure of pure water
• Organisms based on osmotic and salt tolerance

  • Osmophiles
  • Osmotolerant
  • Halophiles
  • Halotolerant
  • Barophiles
  • Barotolerant
• Macronutrients


  Elements required in fairly large amounts
• Micronutrients


  Metals and organic compounds needed in very small amounts
• Carbon


  50% of dry weight, source for the synthesis of the protoplasm of bacteria
• Nitrogen


  12% of dry weight, mainly incorporated in proteins and nucleic acids
• Nitrogen fixers


  Can utilize atmospheric nitrogen (N2)
• Phosphate, Sulfur, Potassium, Magnesium, Calcium, Sodium, Iron


  Other macronutrients required