Although the application of traditional biotechnology can be linked to a number of detrimental effects on the environment, modern biotechnological methods appear poised to reduce the levels of GHGs being released into the atmosphere.

Biotechnology, broadly defined as the use of living organisms to achieve human goals, has been practiced for thousands of years, beginning with the domestication of animals and plants. Common usage of the word, however, typically refers to the use of more modern biological methods to achieve many of the same purposes. The term "modern biotechnology" is sometimes used to differentiate contemporary techniques from "traditional biotechnology." Biotechnology is not a scientific discipline in itself but is intrinsically interdisciplinary in nature, involving mostly agricultural techniques at first but more recently combining principles from such fields as microbiology, cell and molecular biology, and engineering.

Biotechnology likely had its origins between 10,000 and 9,000 b.c.e. with the domestication of dogs in Mesopotamia and Canaan. The first crops, consisting of emmer wheat and barley, are thought to have been grown in this same area within the following millennium. At this time, human impact on the environment was minimal, but as more land was subsequently cleared for the growing of crops and the raising of livestock, the potential to affect the environment increased, albeit slowly. These changes accelerated following the Industrial Revolution, as technologies to modify Earth's landscape were developed. By the late twentieth century, deforestation had become a major contributor to atmospheric carbon dioxide (CO2) levels, while livestock could be linked to the release of methane, another greenhouse gas (GHG), into the atmosphere.

Around this time, biotechnology underwent a revolution, as scientific breakthroughs made it possible directly to change the genetic makeup of virtually any organism. Prior to this, desired changes in organisms had been achieved primarily by selective breeding, a slow and inexact process. Beginning in the 1970's, techniques were developed that allowed scientists to cut deoxyribonucleic acid (DNA) at specific sequences (using purified enzymes called restriction enzymes) and to "glue" these liberated fragments of DNA into a vector that allowed for their propagation in host organisms, thereby cloning a particular gene or DNA segment. This entire process, sometimes called recombinant DNA technology, greatly altered both the speed and the scope of the genetic changes that could be achieved in targeted organisms.

It was not long before recombinant techniques had led to such outcomes as the production of human insulin in the bacterium Escherichia coli (in 1982), the production of ethanol from sugar in the same microbe (in 1991), and the development of a tomato that instead of ripening on the vine, could be picked while green and artificially ripened following shipping (in 1992). These particular examples represent the first applications of modern techniques in three different categories of biotechnology: medicine ("red biotechnology"), environmental science ("white biotechnology"), and agriculture ("green biotechnology"). The first category quickly became dominant over the other two in terms of money invested in the science, accounting for nearly 90 percent of venture capital in the twenty-five years following its introduction. The other two categories split the remaining investments nearly equally during the same time period.

Sometimes called "environmental biotechnology," white biotechnology has been utilized to clean up contaminated environments via bioremediation, prevent the discharge of pollutants from currently existing industries, and generate resources in the form of renewable chemicals and biofuels. While bioremediation comprises a large portion of white biotechnology, it is the latter two goals that are expected to have the greatest effects on alleviating global warming.

Recognizing that the burning of fossil fuels is not likely to disappear overnight, scientists have been focusing on the use of living organisms to remove a portion of the CO2 found in fossil fuel emissions. One candidate for this removal is phytoplankton, microscopic aquatic algae. Phytoplankton are known to make up a large portion of the carbon fixation cycle, which converts CO2 (or dissolved carbon) to sugars during photosynthesis, thereby removing it from the surrounding environment. In nature, phytoplankton eventually die and sink to the bottom of the ocean, removing the carbon from circulation, if only temporarily on a geological timescale.

The burning of fossil fuels has the undesirable consequence of releasing into the environment carbon that has been sequestered in this way for millions of years, adding to the "new" carbon that is released from the burning of biomass. Experiments have been performed in which effluents from power plants were passed through columns filled with algae to reduce theirCO2 emissions. One problem that remained, however, was how to dispose of the algae, since simply allowing them to decompose would return the sequestered carbon back to the atmosphere. One possible solution that was explored involved burning dried algal pellets as fuel. Although still resulting in the release of CO2, this burning allowed more energy to be obtained for a given amount of emission.

The burning of biomass for fuel is preferable to the burning of fossil fuels in terms of its effects upon global warming, since this process can be thought of as "CO2 neutral," in that it simply returns to the atmosphere CO2 that was recently sequestered by the organism in question. Biomass made up the majority of fuel prior to the Industrial Revolution, and it is still relied on by about 50 percent of the world's population to meet its daily fuel needs. The widespread use of wood for fuel, however, although technically CO2 neutral, is less desirable than the use of other forms of biofuel, since it contributes to deforestation and utilizes a resource that takes a considerable amount of time to replenish, compared to agricultural products. Another drawback of solid biofuel such as wood or plant waste is that it does not represent a practical replacement for petroleum-based products in automobiles, a major contributor of CO2 emissions, after power stations and industrial processes. Biomass is therefore typically converted into various alcohols, oils, or gases in order to be used in such applications as the powering of automobiles. Conversion to these forms eases its transportation and storage.

The fermentation of crops to obtain ethyl alcohol, or ethanol, was first performed in Egypt around 4000 b.c.e., although it was not known at the time that the process was being carried out by microscopic yeast. The purpose of such fermentation, however, was the brewing of alcoholic beverages, not the production of fuel. It was not until the energy crunch of the 1970's that ethanol began being mass-produced for fuel from either corn or sugarcane, the former conversion being practiced primarily in the United States, with the latter being most prevalent in Brazil. Brazil subsequently emerged as one of the few success stories regarding biofuels, as a result of the somewhat unique situation of having its sugarcane-growing centers in close proximity to its main population centers. This served to reduce shipping costs, while processing costs were contained by using the residual cane waste, or bagasse, as fuel for the processing plants.

In the United States, where the price of ethanol is more closely linked with the price of oil by the increased costs of processing corn and shipping ethanol to major population centers, debate continues on whether its production as a fuel is economically viable. It has been argued that any fuel that directly competes with food crops will result in increased food prices and ultimately lead to the expansion of farming, so that CO2 emissions could actually experience a net increase as a result of U.S. corn ethanol production. At current production efficiencies, it has been estimated that, even if all of the corn grown in America were converted to ethanol, it would be able to replace only about 20 percent of domestic gasoline consumption. In order to solve some of these drawbacks, focus has shifted to the use of genetically modified organisms to efficiently convert the cellulose found in corn stover, the waste equivalent of bagasse, into ethanol for fuel.

One alternative to the production of ethanol as fuel is the use of plant oils in diesel engines. The use of these oils actually dates from the origination, in 1894, of the engine itself, which was designed by its German inventor, Rudolf Diesel, to burn a variety of fuels, including coal dust and peanut oil, in addition to petroleum products. The use of plant oils, or biodiesel, has seen its greatest adoption in Europe, often in conjunction with public transportation fleets, but is increasingly used in the United States as well. Rapeseed oil is typically used in the former case, while soybean oil is a more likely fuel in the latter. Unfortunately, biodiesel has shared many of the same problems that ethanol production from biomass has, including relatively high costs of production, as well as competition with the use of the same crops for food. One possible solution has been the genetic modification of algae so they accumulate excess oil, which can then be purified. Such algae could potentially be grown in aquatic environments that would not compete with the land normally used for food crops.

One biofuel that perhaps holds the most promise is hydrogen gas, H2. While this gas can be easily adapted for use in automobiles or to generate electricity, it differs from the other fuels discussed in that the combustion ofH2 produces no CO2 whatsoever, only water. One technical hurdle that must be overcome is that H2 is normally released at a very low efficiency by the algae and bacteria that are known to produce it. These organisms typically undergo a process called photolysis, where an H2O molecule is split using energy derived from sunlight. The enzyme responsible for creating the H2 gas, however, is inhibited by the presence of the oxygen that is created during photolysis. Genetic engineering may be the key to improving the efficiency of H2 production, so its use as a biofuel may soon be realized.

Throughout the years, humans have used the living things around them to meet their basic needs, as well as to achieve various other purposes, slowly changing these organisms through selective breeding in order to cause them to be better suited for their desired application. Achieving human purposes has not always had a positive effect on the environment, with the domestication of both plants and animals being responsible for steadily releasing large amounts of CO2 and methane into the atmosphere. It has only been fairly recently that humans have acquired the motivation and the technology to begin to address some of these detrimental changes. The ability to change organisms rapidly via recombinant DNA technology may hold the promise of engineering organisms to clean up the environment and to reduce the emissions of greenhouse gases. Although still in its early stages, compared to biotechnology aimed at alleviating medical problems, environmental biotechnology is emerging as one possible solution to the threat of global warming.

Bibliography:

1)         Evans, Gareth M., and Judith C. Furlong. Environmental Biotechnology: Theory and Application. Hoboken, N.J.: John Wiley & Sons, 2003.

2)         Kircher, Manfred. "White Biotechnology: Ready to Partner and Invest In." Biotechnology Journal 1 (2006): 787-794.

3)         Scragg, Alan. Environmental Biotechnology. New York: Oxford University Press, 2005.

4)         Tollefson, Jeff. "Not Your Father's Biofuels." Nature 452 (February, 2008): 880-883.

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