Microbiology 5

• What are the learning outcomes mentioned in the study material?


  Environments, habitats, and abiotic growth factors
• What is the definition of an ecosystem?

  A dynamic complex of communities and surroundings
• What is a microenvironment?

  A tiny local environment experienced by microorganisms
• How does diffusion affect resource availability for small organisms?

  Diffusion often determines resource availability
• What happens to oxygen levels in a small soil particle?

  Outer layers are oxic, inner layers are anoxic
• What is the role of microorganisms in the rhizosphere?

  Microbes absorb nutrients exuded by roots
• What factors affect water availability in soil?

  Soil composition, rainfall, drainage, plant cover
• Where does the greatest microbial activity occur in soil?

  In organic-rich soil surface layers
• What is groundwater?

  Water in soils and rocks deep underground
• How deep can microbial life extend into the Earth?

  At least 3 km deep
• What is the significance of chemolithotrophic bacteria found at 3 km deep?

  They survive on a nutrient-poor diet
• What are the differences between freshwater and marine habitats?

  Salinity, temperature, depth, nutrient content
• What are oxygenic phototrophs?

  Organisms that produce energy from light
• How does the water column in lakes change with depth?

  It becomes stratified with different layers
• What happens to oxygen levels in organic-rich wastewater?

  Oxygen decreases due to bacterial respiration
• What are hydrothermal vents?

  Underwater hot volcanic springs

  
• What are the abiotic growth factors for organisms?

  Nutrient availability, temperature, pH, moisture, oxygen, pressure, light
• What are cardinal temperatures?

  Minimum, optimum, and maximum growth temperatures
• How does pH affect microbial growth?

  Most microbes grow within a 2-3 pH unit range
• What are the different oxygen requirements for microbes?

  Aerobic, anaerobic, facultative, microaerophilic, aerotolerant
• What characterizes aerobic microorganisms?

  They grow at full oxygen tensions
• What defines anaerobic microorganisms?

  They cannot respire oxygen and are inhibited by it
• What is a facultative microorganism?

  It can grow in both oxic and anoxic conditions
• What are microaerophiles?

  Aerobes that require lower oxygen levels than air
• What are aerotolerant organisms?

  Anaerobes that can tolerate but do not use oxygen
• What are the key points about microbial ecology?

  • Microbes have their own ecology.
  • Environments differ in supporting microbial populations.
  • Microbes live in specific habitats.
• What are the main types of habitats for microbes?

  • Terrestrial
  • Aquatic
  • Freshwater
  • Coastal/Ocean
  • Deep Sea
• What are the important abiotic growth factors for microbes?

  1. Nutrient availability
  2. Temperature
  3. pH
  4. Moisture
  5. Oxygen
  6. Pressure
  7. Light
• What are the different types of microbial oxygen requirements?

  • Aerobic
  • Anaerobic
  • Facultative
  • Microaerophilic
  • Aerotolerant
• What is the significance of microbial growth in soils?

  • Most growth occurs on soil particle surfaces.
  • Promoted in the rhizosphere due to nutrient exudation.
• How do microbial populations vary in groundwater?

  • Cell numbers vary by orders of magnitude.
  • Variation is due to nutrient availability.
• What are the effects of temperature on microbial growth?

  • Each species has minimum, optimum, and maximum temperatures.
  • These are known as cardinal temperatures.

  
• What is the role of oxygen in microbial habitats?

  • Oxygen is poorly soluble in water.
  • Anoxic habitats are common in various environments.
• What are the implications of microbial diversity in ecosystems?

  • Microbes are crucial for nutrient cycles.
  • They contribute to ecosystem functions and health.