Biology In Human Welfare Microbes In Human Welfare 2

Microbes in biogas production :#

What is Biogas?

• Mixture of gases predominantly containing methane
• Produced by microbial activity
• Used as fuel

Methanogens:

1. Key bacteria involved in biogas production
2. Grow anaerobically on cellulosic material
3. Produce:
   • Methane (CH4)
   • Carbon dioxide (CO2)
   • Hydrogen (H2)
4. Example: Methanobacterium

Sources of Methanogens:

1. Anaerobic sewage sludge
2. Cattle rumen (stomach)
3. Cattle dung (gobar)

Biogas Plant Structure:

1. Concrete tank (10-15 feet deep)
2. Collection of bio-wastes and dung slurry
3. Floating cover over slurry
4. Gas outlet pipe for supply
5. Outlet for spent slurry (used as fertilizer)

Benefits and Applications:

1. Primarily used in rural areas
2. Applications:
   • Cooking
   • Lighting
3. Readily available cattle dung as raw material

Development:

• Technology developed in India through:
  1. Indian Agricultural Research Institute (IARI)
  2. Khadi and Village Industries Commission (KVIC)

Microbes as biocontrol agents:#

1. Introduction to Biocontrol

• Uses biological methods to control plant diseases and pests
• Alternative to chemical pesticides and insecticides
• Environmentally friendly approach

2. Problems with Chemical Control

• Toxic to humans and animals
• Pollutes environment (soil, groundwater)
• Contaminates fruits, vegetables, and crops
• Soil pollution through weedicides

3. Organic Farming Approach

• Relies on natural predation
• Promotes biodiversity
• Maintains pest populations at manageable levels
• Creates balanced ecosystem
• Holistic approach considering all organisms

4. Types of Biocontrol Agents

a) Natural Predators:

• Ladybird beetles (controls aphids)
• Dragonflies (controls mosquitoes)

b) Bacterial Agents:

• Bacillus thuringiensis (Bt)
• Controls butterfly caterpillars
• Available as dried spores
• Bt genes can be engineered into plants (e.g., Bt-cotton)

c) Fungal Agents:

• Trichoderma species
• Found in root ecosystems
• Controls plant pathogens

d) Viral Agents:

• Baculoviruses (Nucleopolyhedrovirus)
• Species-specific
• No negative impact on other organisms
• Suitable for integrated pest management (IPM)

5. Benefits of Biocontrol

• Reduces dependency on toxic chemicals
• Environmentally safe
• Preserves beneficial organisms
• Sustainable approach
• Species-specific control

Microbes as biofertilizers#

1. Introduction to Biofertilizers:

• Alternative to chemical fertilizers due to environmental concerns
• Organisms that enrich soil nutrient quality
• Main sources: bacteria, fungi, and cyanobacteria

2. Bacterial Biofertilizers: a) Rhizobium

• Forms symbiotic nodules with leguminous plants
• Fixes atmospheric nitrogen into organic forms
• Provides nutrients to host plants

b) Free-living nitrogen fixers

• Azospirillum and Azotobacter
• Fix atmospheric nitrogen in soil
• Enhance soil nitrogen content

3. Fungal Biofertilizers (Mycorrhiza):

• Genus Glomus forms symbiotic associations with plants
• Benefits to plants:
  • Absorbs and transfers phosphorus from soil
  • Increases resistance to root pathogens
  • Improves drought and salinity tolerance
  • Enhances overall plant growth

4. Cyanobacterial Biofertilizers:

• Autotrophic microbes found in aquatic and terrestrial environments
• Examples: Anabaena, Nostoc, Oscillatoria
• Benefits:
  • Fix atmospheric nitrogen
  • Add organic matter to soil
  • Particularly useful in paddy fields
  • Increase soil fertility

5. Current Status:

• Many commercial biofertilizers available in market
• Widely used by farmers
• Helps reduce dependence on chemical fertilizers
• Contributes to sustainable agriculture