Bài giảng - Applications of microbes in environment and agriculture

Applications of Microorganisms
in Agriculture and Environment


Applications of
Microorganisms in
Environment


Bioremediation
is the use of microorganism metabolism
to remove pollutants


We Use Existing Microbes
 To clean up oil spills


Decomposition by Microbes

Components of agent orange

Figure 27.8


We Use Existing Microbes
 To leach ores


In addition to the oxidation of sulfur and sulfur
compounds Thiobacillus ferrooxidans is able

to oxidize ferrous to ferric iron and so derive
its energy from this exergonic reaction
2Fe++ + 2H+ + ½O2  ---->    2Fe+++ + H20 
2Fe+++ + 6H20       ---->    2Fe(OH)3 + 6H+
2Fe++ + 5H20 + ½O2   ---->    2Fe(OH)3 + 4H+ 


Wastewater treatment


Anaerobic Sludge Digester
 CO2 + 4 H2  CH4 + 2 H2O
 CH3COOH  CH4 + CO2

Figure 27.23


We Use Existing Microbes

 To turn trash into soil


Applications of
Microorganisms in Agriculture


Basic Principles of
Recombinant DNA
Technology

Definition
The transfer of genetic information from
one organism to another
 Methods and techniques are known as
Recombinant DNA Technology




Steps in Recombinant DNA
Technology
1. Cleaving (cutting) the target DNA
2. Ligating the target DNA into a vector
3. Transformation of a host cell with the

recombinant DNA (vector DNA with
DNA insert)
4. Screening of cells for those harboring
the recombinant DNA or producing the
appropriating protein product


Examples of applications of
genetic engineering in agriculture
Insect resistant plants
Corn borer
– pest of corn in North America and
Europe
– Lepidoptera (moths and butterflies)

– Bt-corn for corn borer control


What is Bt and how does it work?

 Bacterium Bacillus thuringiensis produces protein, delta-endotoxin,
that is toxic to insects in orders Lepidoptera, Coleoptera (beetles)
- Bt toxin in form of powder used as insecticide spray  applied
to leaves where larvae feed on
Mode of action:
1. Insect eats Bt crystals ( ) and
bacterial spores. Bt crystals dissolve at
high pH in insect gut.
2. Toxin binds to specific receptors in gut
and insects stops eating.
3. Toxin causes the gut wall to break
down, allowing spores and normal gut
bacteria to enter the body.
4. Insect dies as spores and gut bacteria
proliferate in the body.


Genetic engineering of Bt-resistant corn (Bt-corn)
 Clone Bt toxin gene from bacteria and express in plants

 Bt-transgenic plants are resistant to insects, no need for spraying
insecticide


Bt-crops for corn borer control

 Currently in crops of
corn (control of corn borer)
cotton (control of bollworm)
 Studies that demonstrate harmful effects of Bt
corn on other insects and ecosystems
 effect of Bt-transgenic corn on Monarch
butterfly larvae feeding on milkweed?
Bt corn may harm stream ecosystems


Bt corn may harm stream ecosystems

Bt corn may harm the caddishfly, which serves as food for
fish and amphibians. Parts of Bt corn, such as leaves, cobs
and pollen, can travel as far as 2000 meters away from
source areas-a phenomenon that was not considered when
Bt corn was licensed.


Biofuels – Alternatives to Corn

Jatropha curcas - an important feedstock for the production of biofuels.
- widespread use in India and Egypt
- fast growing source of oil-bearing nuts that can be pressed to produce
biodiesel
- oil for use in generators, sewing machines and small motors
- Glycerin, a by product of Jatropha oil, can also be used to produce soap

Genetic engineering of freezing
tolerance in Canola
Control and CBF-canola
before freezing

Controls

CBF-Canola

Control and CBF-canola
after 2 days @ -6oC

Controls

CBF-Canola