Oil spills and Marine Biotechnology
A. Brief about Oil Spills –
1. Characteristics of oil spills are:
* Unintentional discharge of liquid hydrocarbons into environment.
* Contain many types of oil, including crude oil, refined petroleum, and oil mixed with waste.
* Immiscible with water, so oil can remain on surface for lengthy periods of time.
* Can greatly affect the environment and biological web in location where spill occurred.
2. Effects of oil spills are:
* Smothering of plants and animals due to oil’s stickiness and buoyancy.
* Disruption of nutrient cycle due to large increase in hydrocarbons.
* Toxicity due to water soluble portions in oil can lead to mutations in organisms that stunt growth, metabolism, reproduction, and other biological functions.
3. Clean-up of oil spills:
a. Mechanical response -
* Booms and other physical devices aid in clean up.
* Oil is collected into confined area to prevent spread, physically recovered by skimming surface with boats or vacuums
b. Chemical response -
* Oil broken down with chemicals into constituents, dispersed to decrease harm to wildlife.
* In-situ burning involves igniting the oil while still on the ocean surface.
Both approaches leave pollutants and are quite costly, so a better method is desired by environmentalists, corporations, and governments.
B. Possible solution to Oil Spills (Biotechnological way) –
* Certain marine microorganisms have the unique ability to break down hydrocarbons to access energy stored in bonds; they are capable of inserting an oxygen atom into hydrocarbon to form a degradable alcohol or carboxylic acid.
* First tested on a large scale to some success in the Exxon-Valdez spill in 1989.
* Microorganisms are especially good at cleaning up last stages of an oil spill, attacking persistent compounds that other techniques failed to break down.
C. The problems that plague oil spill bioremediation through microorganisms -
* Oil spills involve many different compounds with different chemical structures, but biodegrading bacteria are usually specific to one compound.
* Biodegrading bacteria use the oil compounds as energy sources, so if the concentration of the compounds is low then the bacteria are unable to produce enzymes that break the compounds down.
* Certain compounds are promptly absorbed by the soil or water around the spill, diluting them to a concentration where they can no longer function as the energy sources of the biodegrading bacteria.
* A spill could contain other compounds that harm the biodegrading bacteria instead of providing energy.
D. The Question –
Is it possible to genetically modify a microorganism to make it digest multiple compounds that can appear in an oil spill?
E. What’s been done so far?
* Cloning vectors that specialize in environmental applications are being developed to produce more microorganisms at the site of the spill.
* Rate limiting enzyme reactions can prevent maximum efficiency of hydrocarbon breakdown, so mechanisms to overcome these limits have been developed.
* Some genes that code for multifunctional activity in microorganisms have been discovered.
* Extremophiles that can withstand high temperatures, changes in pH, and a decrease in nutrients like oxygen have been discovered/developed.
* Microorganisms like Alcanivorax borkumensis which specify in aerobic decomposition of hydrocarbons have been discovered, providing a base organism to genetically modify.
F. What needs to be done?
* Identify the different marine microorganisms that break down hydrocarbons; many of these have already been identified since they reproduce rapidly near oil spills.
* Sequence identified microorganisms’ genomes, locate the genes that code for hydrocarbon breakdown and isolate these genes from the bacterial DNA.
* Insert these genes into a base microorganism (in this case, Alcanivorax) utilizing a DNA vector (plasmid) and test GMO on small sample of mixed oils.
* If GMO is able to degrade multiple hydrocarbons, success!
G. Conclusion –
* Oil spills can be extremely harmful to the environment and need to be cleaned up in efficient, cheap ways.
* Certain marine microorganisms can break down complex hydrocarbons for energy, and in the process can clean up spilled oil in a natural manner.
* These bacteria are structure specific, making it hard for one microorganism to clean up a mix of oil.
* A genetically modified organism that can break down multiple compounds could be used to clean spills very efficiently.
* A bacterium like Alcanivorax borkumensis could provide the base for such an organism.
* This GMO could be created by inserting the gene that codes for different hydrocarbon breakdown into Alcanivorax through a plasmid and then tested for efficiency.
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