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Sunday, October 14, 2012

Composting: Vermicomposting

Composting is the biological degradation of solid organic waste into stable end products. The term compost applies to a considerable number of  composted materials produced from a variety of sources. In its broadest sense , it includes any organic material that has undergone managed aerobic microbial degradation at elevated temperatures, resulting in significant microbial, physical and chemical changes to the original material. These composts have been produced using source-separated materials derived from green wastes, kitchen wastes and wood wastes and may also include animal manure but are not derived exclusively from them.

Composting: Vermiculture
Soil Fauna - Termites and Earthworms  - play vital role in maintaining soil quality and also in managing efficient nutrient cycling

The Composting Process
Composting can be defined as the biological decomposition and stabilization of organic substrates, under conditions that allows thermophilic temperature as a result of biologically produced heat 

Aerobic Composting

•Composting with decomposers that need air (oxygen)

•The fastest way to make high quality compost

•Produces no foul odors

•Aerobic decomposers produce heat

•Active composting occurs in the temperature range of 55oF to 155oF,

Pile temperature may increase above 140oF but this is too hot for most bacteria and decomposition will slow until temperature decreases again

Vermicompost - Making compost with the use of earthworms.

vermicompost process

  • Its a stable fine granular organic matter added to the clay soil helps loossen the soil and allows to passage for the entry of air.
  • Mucous associated with the cast can absorb water which prevents logging, improves water holding capacity.
  • Improves physical/chemical/biological properties of soil.
  • Yield of crop is increased.
  1. Easy Management.
  2. Vermicomposting wastes as source - Profitably utilized and commercialized for economic gains.
  3. Domestic, agricultural, rural industrial organic wastes can be recycled for various usages which will help in reducing pollution.
  4. Loss of nutrients by leaching + nutrient loss is minimal.
  1. Less extent of damaging crops.
  2. Casts - as ugly structures in ornamental lawns.
  3. Occasionally transmits many parasites and disease of plants and animals.

Vermiculture Process
  1. Site Selection.
  2. Availability of decomposible organic waste, daily quantity and quality, etc.
  3. Marketable outlet and requirement with future scope.
  4. Collection and study of earthworm culture.
  5. Testing.
  6. Maintenance of seed culture.
Vermicomposting Materials
  • Animal dung, Agricultural wastes
  • Industry wastes
  • City leaf litter
  • Waste paper and cotton cloth etc.
  • Biogas Slurry
Primary Treatment of Composting material
  1. Sorting, Separation.
  2. Exposure to sun for a day.
  3. Mixing of daily organic waste products.
Indoor Vemicomposting

how to do vermicompost

Moisture Content - 30 - 40%
Temperature - 20 - 30oC
  • Earthworms - Perionyx excavatus, Eudrilus eugeniae
  • Biological indicators of soil activities - used for monitoring and maintaining biological health of soil.

Saturday, October 13, 2012

Stratagies to Improve Bactrial Disease Resistance in Plants through Genetic Engineering

1. Production of Anti Bacterial Proteins of Non-Plant Origin
  • Lytic Peptides from Insects
  • Lysozymes
  • Other antibacterial Peptides
2. Inhibition of Bacterial Pathogenicity or Virulence Factors
  • Inhibition of Bacterial toxins
  • Other Approached
3. Enhancement of Natural Plant Defenses
  • Enhanced Production of Elicitors 
  • Expression of cloned resistant genes
  • Enhanced production of reactive oxygen species
  • Expression of plant defense genes 
4. Artificially Induced Programmed Cell Death at the site of infection
  • R and avr genes
  • Barnase and Barstar genes
  • Bacterio-opsin gene

Production of anti-Bacterial Proteins of Non-Plant Origin:

a) Lytic Peptides from Insects:
  •  Small Proteins with alpha helices
  • Causes pores in bacteria
    Example: Cecropins, attacins – giant silk moth 
  •  Synthetic analogs of cecropin gene – Potato, Tobacco. 
  •  Transgenic tobacco – bacterial wilt – delayed mortality. 
  •  Limitation: Degradation of cecropins by plant proteases. 
b) Lysozyme
  •  Lysozymes are ubiquitous enzymes. 
  • Hydrolytic bacterial cell wall containing peptidoglycan. 
  •  Transgenic tobacco- hen egg lysozyme – resistance to several species. 
  •  Transgenic potato – T4 Bacteriophage – Partial resistance to Erwinia. 
  •  Transgenic tobacco- human lysozyme – Partial resistance to P.syringae. 
c) Other antibacterial peptides

  • Iron binding glycoprotein
  • Bactericidal properties
Transgenic Tobacco
  • Human Lactoferin gene
  • Delayed symptoms on Rhizoctonia solanaceae
  • Codes for lytic peptides
  • Horseshoe crab.
Transgenic potato:
  • genes from horseshoe crab - partial resistance.
  • Limitation: Expressed reduced amount of tuber.

Inhibition of Bacterial Pathogenicity or Virulence Factors

a) Inhibition of bacterial toxins

Pathogen protects itself against toxin by expressing tabtoxin resistant genes (ttr), transgenic tobacco with genes show resistance towards many bacteria.

b) Other Approaches

3. Enhancement of Natural Plant Defenses

a) Enhanced Production of Elicitors

b) Expression of cloned resistant genes

c) Enhanced production of reactive oxygen species

A glucose oxidase gene from A.niger is cloned into potato plants resulted in resistance. This enzyme induce large amount of hydrogen peroxide. transgenic potato results in increased level of resistance.

d) Expression of plant defense genes

In certain cases resistance was not seen though high level of thionin is produced. This may be due to thionin is secreted into intracellular space, where bacteria are generally found.

Plant defense mechanism is due to battery of synergetic reactions. Hence the expression of combination of heterologous genes would be more promising

4. Artificially Induced Programmed Cell Death at the site of infection

  • R and avr genes applied to fungus
  • Barnase and Barstar genes
  • Barnase - Bacterial ribonuclease gene
  • Barstar - Inhibitor of barnase
  • Bacterial opsin gene
  • Efficacy, durability, absence of toxicity and low environmental impact
  • Gene silencing