Nutritional Types of Microbes

Nutritional Types of Microbes

• Microbes are classified by their requirements for carbon, energy, and electrons for growth

• Based on Energy Source:

  • Phototrophs: Obtain energy from light (photosynthesis)
    • Examples: Purple sulfur bacteria, green sulfur bacteria, green plants, algae, cyanobacteria
  • Chemotrophs: Obtain energy from chemical compounds
    • Examples: Sulfur-oxidizing bacteria, nitrifying bacteria, iron-oxidizing bacteria, fungi (like Aspergillus and Penicillium)

• Based on Carbon Source:

  • Autotrophs: Produce their own organic compounds from inorganic sources (like CO2)
    • Photoautotrophs: Use light energy and CO2 for photosynthesis
      • Examples: Cyanobacteria, green plants
    • Chemoautotrophs: Oxidize inorganic substances for energy and use CO2 for carbon
      • Examples: Sulfur-oxidizing bacteria
  • Heterotrophs: Obtain organic carbon from other organisms
    • Photoheterotrophs: Use light energy but need organic carbon
      • Examples: Purple non-sulfur bacteria, green non-sulfur bacteria
    • Chemoheterotrophs: Obtain energy and carbon from organic compounds
      • Examples: Most bacteria, fungi, humans, animals

• Based on Electron Source:

  • Lithotrophs: Use reduced inorganic substances as electron source
    • Lithoautotrophs: Use inorganic compounds for both energy and carbon
    • Lithoheterotrophs: Use inorganic compounds for energy and require organic carbon
      • Examples: Sulfur-oxidizing bacteria, iron-oxidizing bacteria, ammonia-oxidizing bacteria (nitrifying bacteria)
  • Organotrophs: Use organic compounds as electron source
    • Examples: Humans, animals, fungi (like Aspergillus, Penicillium), bacteria (like Escherichia coli, Clostridium)

Additional Points

• Chemosynthesis: The process where chemoautotrophs convert CO2 into organic compounds using energy released from chemical reactions.
• Processes like photosynthesis and cellular respiration/fermentation are involved in energy production and metabolism for microbes.