B.Sc. Industrial Microbiology III: Habitat Ecology

Structure and Function of Ecosystem

• An ecosystem consists of biotic (living organisms) and abiotic (physical environment) components, interacting as a system.
• Energy flows through the ecosystem via food chains and webs, while nutrients cycle among organisms and the environment.
• Key processes include photosynthesis, respiration, decomposition, and nutrient cycling, maintaining ecosystem health and balance.

Terrestrial Environment

• Soil profile consists of layers (horizons): organic matter (O horizon), topsoil (A horizon), subsoil (B horizon), and bedrock (C horizon).
• Soil microflora includes bacteria, fungi, actinomycetes, and algae, which play crucial roles in:
  • Nutrient cycling
  • Organic matter decomposition
  • Soil structure maintenance

Aquatic Environment

• Freshwater habitats contain microflora like bacteria, cyanobacteria, algae, and protozoa, essential for:
  • Nutrient cycling
  • Water purification
• Marine habitats host diverse microflora, including phytoplankton, bacteria, and archaea, which contribute to:
  • Primary production
  • Biogeochemical cycles
  • Marine food webs

Atmospheric Environment

• Aeromicroflora consists of airborne microorganisms like bacteria, fungi, and viruses.
• These microbes are dispersed through air currents, weather events, and human activities.
• Aeromicroflora impacts:
  • Air quality
  • Human health
  • Atmospheric processes (cloud formation, nutrient cycling)

Animal Environment

• Human microbiome includes bacteria, fungi, viruses, and archaea residing in and on the human body.
• These microbes aid:
  • Digestion
  • Immune function
  • Overall health
• In ruminants, microbes in the stomach (rumen) help:
  • Break down cellulose
  • Ferment plant materials
  • Nutrient absorption and energy production

Extreme Habitats

• Extremophiles are microbes that thrive in extreme conditions, including:
  • High/low temperature
  • Extreme pH
  • High hydrostatic pressure
  • High osmotic pressure
  • Low nutrient levels
• These microbes adapt through specialized enzymes and cellular structures.

Microbial Succession in Decomposition

• Microbial succession in plant decomposition involves a sequence of microbial communities breaking down organic matter.
• The process involves:
  • Initial degradation of simple compounds by bacteria and fungi
  • Breakdown of cellulose by cellulolytic microbes
  • Decomposition of complex molecules by lignin-degrading fungi
  • Recycling of nutrients back into the ecosystem

Microbial Interactions

• Microbial interactions encompass various relationships among microorganisms and between microorganisms and their environment.
• These interactions determine the structure and function of microbial communities.
• Types of microbial interactions include:

  Mutualism

  • Definition: A symbiotic relationship where both organisms benefit.
  • Example: Lichens (mutualistic relationship between fungi and photosynthetic algae or cyanobacteria)

  Synergism

  • Definition: An interaction where two organisms work together to achieve a result that neither could accomplish alone.
  • Example: Certain bacteria and fungi working together in soil to degrade complex organic compounds

  Commensalism

  • Definition: A relationship where one organism benefits, and the other is not affected.
  • (Example not provided)