Transgenic bacteria

Manjunath, G.A

What are GMO’s?

Genetically Modified Organisms are organisms that

have been genetically altered to carry and/or produce

a certain necessary gene. This is done by inserting the

required gene into the organism’s DNA.

There are three types of GMO’s: animals, plants and

bacteria

We focused on bacteria.

How are GMO’s made?

A specific gene is chosen and then extracted from DNA

using a restriction enzyme.

This gene is then inserted into a bacterium. Since these

are single celled organisms the gene only has to be

inserted once and because bacteria multiply quickly,

they are an ideal candidate for mass production of a

specific gene.

Why is it relevant to society?

GM bacteria are relevant to society, because they are a

fast and easy way to make a lot of a selected gene.

They can be used to cure and prevent sicknesses,

to create medicines, to improve the

environment in numerous ways and to help

in many other ways.

Benefits of GM Bacteria

In the Environment- Possible control of weeds and use of GMOs that reduce the use of toxic chemicals, GMOs to decontaminate toxic waste sites, GMOs in environmental friendly power

In Farms- Improved nutrition for people, increased environmental protection through the reduced use of pesticides, and increased quality and quantity of yields, as well as increased farm profitability through reduced costs and new product opportunities

Degradation of oil spill : gene that synthesize lipase (fat digesting enzyme) from animal is inserted into bacteria

Used to clean oil spill that cause water pollution.

Nitrogen fixation : producing bacteria that can fix nitrogen to increase crops production.

Anti-freezing bacteria (transgenic) is sprayed to the plants to prevent the ice formation.

Eg : tomatoes, strawberries

Transgenic plant

transgenic plant: plants that has useful foreign

genes from another species.

Has desirable improved characteristics

- e.g: Pests and herbicides resistance, delay

ripening, improve flavour

1985

1992

1988

1994

1998

1996

1999

2000

1st transgenic plants produced

Particle bombardment developed

GM crops considered substantially equivalent to hybrid varieties

Flavr-Savr tomato is released

Herbicide- and insect-resistant crops approved for cultivation

4.3 million acres of GM crops planted

GM food is dangerous (UK TV)

Monarch butterfly paper causes uproar

GM corn is excluded from its baby food

Greenpeace starts anti-GM campaign

75 million acres of GM crops planted

Golden rice with ß-carotene developed

McDonald’s rejects GM potatoes

TRANSGENIC PLANTS

NUTRITIONAL

QUALITYBIOTIC STRESS

TOLERANCE

ABIOTIC STRESS

TOLERANCE

PHARMACEUTICALS

& EDIBLE VACCINE

HYBRID DEVELOPMENT

FOR HIGHER YIELD

ENHANCED

SHELF LIFE

INDUSTRIAL

PRODUCTS

Important Traits for Crop Improvement

High crop yield

High nutritional quality

Abiotic stress tolerance

Pest resistance

Adaptation to inter-cropping

Nitrogen Fixation

Insensitivity to photo-period

Elimination of toxic compounds

Insect Resistance

Delayed Fruit Ripening

Nutritional Enhancing

Herbicide Resistance

Virus Resistance

The big five successful traits

Resistance to herbicideGene for herbicide resistance can be inserted into a crop plant’s chromosomal

DNA

Herbicides will have no effect on the transgenic crop plants and only destroy the

weeds

Glyphosate Resistance

i. Glyphosate = “Roundup”, “Tumbleweed” = Systemic herbicide

ii. Marketed under the name Roundup, glyphosate inhibits the enzyme EPSPS (S-enolpyruvlshikimate-3 phosphate – involved in chloroplast amino acid synthesis), makes aromatic amino acids.

iii. The gene encoding EPSPS has been transferred from glyphosate-resistant

E. coli into plants, allowing plants to be resistant.

Glufosinate Resistance

i. Glufosinate (the active ingredient being phosphinothricin) mimics the structure of the amino acid glutamine, which blocks the enzyme glutamate synthase.

ii. Plants receive a gene from the bacterium Streptomyces (bar gene) that produce a protein that inactivates the herbicide.

Herbicide Resistance

Bromoxynil Resistance

i. A gene encoding the enzyme bromoxynil nitrilase (BXN) is transferred from Klebsiella pneumoniae bacteria to plants.

ii. Nitrilase inactivates the Bromoxynil before it kills the plant.

Sulfonylurea.

i. Kills plants by blocking an enzyme needed for synthesis of the amino acids valine, leucine, and isoleucine.

ii. Resistance generated by mutating a gene in tobacco plants (acetolactate synthase), and transferring the mutated gene into crop plants.

Herbicide Resistance

Roundup Ready™ Soybeans

A problem in agriculture is the reduced growth of crops imposed by

the presence of unwanted weeds. Herbicides such as Roundup and

Liberty Link are able to kill a wide range of weeds and have the

advantage of breaking down easily. Development of herbicide

resistant crops allows the elimination of surrounding weeds without

harm to the crops.

Insect resistance

a) Toxic crystal protein from Bacillus thuringensis

Toxic crystals found during sporulation

Alkaline protein degrades gut wall of lepidopteran larvae

Corn borer catepillars

Cotton bollworm catepillars

Tobacco hornworm catepillars

Gypsy moth larvae

The Bt toxin isolated from Bacillus thuringiensis has been used in plants. The gene has been placed in corn, cotton, and potato, and has been marketed.

Insect Resistance

Corn hybrid with a Bt gene Corn hybrid susceptible to European

corn borer

Various insect resistant crops have been produced. Most of

these make use of the Cry gene in the bacteria Bacillus

thuringiensis (Bt); this gene directs the production of a protein

that causes paralysis and death to many insects.

δ -endotoxin gene (Cry gene) of Bacillus thuriengenesis

GENE FOR Bt TOXIN WAS TRANSFERRED

TO OBTAIN BT TRANSGENIC PLANTS

PLANT SYNTHESIZES INACTIVE PROTOXIN

PROTEINASE

DIGESTION IN

INSECT GUT

MAKES THE

ACTIVE TOXIN

Toxin binds a receptor on the gut epithelial cells, forms a channel

on the membrane. This causes electrolyte leakage and insect death

INSECT FEEDS ONTRANSGENIC PLANT

a) Allow for crops, such as tomatoes, to have a higher shelf life.

b) Tomatoes generally ripen and become soft during shipment to a store.

c) Tomatoes are usually picked and sprayed with the plant hormone ethylene to induce ripening, although this does not improve taste

d) Tomatoes have been engineered to produce less ethylene so they can develop more taste before ripening, and shipment to markets

Delayed Fruit Ripening

What happened to the Flavr Savr tomato?

i. Produced by blocking the polygalacturonase (PG) gene, which is involved in spoilage. PG is an enzyme that breaks down pectin, which is found in plant cell walls.

ii. Plants were transformed with the anti-sense PG gene, which is mRNA that base pair with mRNA that the plant produces, essentially blocking the gene from translation.

iii. First genetically modified organism to be approved by the FDA, in 1994.

iv. Tomatoes were delicate, did not grow well in Florida, and cost much more than regular tomatoes.

v. Calgene was sold to Monsanto after Monsanto filed a patent-infringement lawsuit against Calgene, and the Flavr Savr tomato left the market.

Delayed Fruit Ripening

First biotech plant product – Flav’r Sav’r tomato

“Rot-Resistant Tomato”

Colorful Cauliflowers

Purple tomatoes

The disadvantages of genetically modified

crops are:

Proteins produced by GM organisms may cause allergies and other diseases

Persistent release of insecticidal proteins by GMO’s may disrupt the

biological activity of the soil.

Horizontal transfer of antibiotic resistant genes from transgenic crops to

bacteria

The genetically modified crops may eliminate the indigenous varieties

through competition for minerals and nutrients

Environmental risk of crop developed using GMO’s

Genetically modified crops may turn benign organisms into destructive

pests.