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Team:BGU Israel/Consequences
From 2013.igem.org
1. Introduction
Releasing GMOs that are suspected to be safe into the environment does not guarantee that there will be no side effects or ecological damage. Furthermore, using dangerous GMOs for harmful purposes is a possibility that cannot be ignored. Quantifying the probability of each scenario is challenging, and it is even more problematic to predict and imagine the unexpected. In the following analysis, different scenarios are proposed, and the potential consequences discussed.
2. Properties of Recombinant Organisms
The following properties of recombinant organisms are relevant for evaluating each occurrence: 1. Bacteria are not easy to remove once released into the environment. 2. Commonly used micro-organisms are characterized by fast generation rates. 3. Most of these micro-organisms are able to adapt to adverse environmental conditions. 4. The exchange of genetic material between different species, called horizontal gene transfer (HGT), is very common. Bacteria are the only organisms capable of natural transformation.
3. Potential Risks of the Release of GMOs to the Environment
Genetic engineering could potentially give rise to micro-organisms with entirely unknown pathogenic properties, or micro-organisms with highly damaging environmental effects. Antibiotic resistance is another concern: the selection of resistant bacterial strains containing plasmids and transfer of these plasmids into other micro-organisms could bring about the spread of resistance to antibiotics.
4.1 Short-Term GMOs
It has been suggested that natural micro-organisms and genetically engineered micro-organisms would not compete in the same ecological niche. Once a genetically engineered micro-organism designed for a task such as bioremediation has completed its purpose (i.e. its nutrient supply is exhausted), it should be unable to compete with natural micro-organisms that are better adapted for the environment. For example, after a genetically engineered micro-organism specifically designed to metabolize oil into harmless by-products has consumed the oil, it should die off. However, like all natural species, a population of genetically engineered micro-organisms is subject to natural mutations, recombination, and selective pressures. Therefore, the introduced micro-organisms could continue to exist in the environment if they develop the capability to utilize new food sources, and would not be driven to extinction unless they were at a significant disadvantage to their competitors. Here, our project offers a solution: the insertion of an autonomous self-destruct mechanism significantly reduces the risk that a GMO population would survive beyond the completion of its intended task. (For more, see: Our Solution)
4.2 Long-Term GMOs:
Eventually, there may be applications or projects that require the establishment of persistent populations of GMOs. Such populations must be capable of surviving long-term in niches previously unfilled, or to effectively compete with natural species, and therefore are more likely to lead to unwanted environmental effects. The survival of genetically engineered micro-organisms past their intended period of usefulness is not the only potential issue: bacteria can exchange genetic material with other micro-organisms relatively easily. This process is called gene transfer, and can occur during conjugation. In such a case, genes could persist in the natural environment even after the GMO population has died out. In general, gram-negative and gram-positive bacteria, which can co-exist in natural aquatic and terrestrial environments, exchange plasmids exclusively with members of their own group; many restrict exchange to their own species. However, some "promiscuous” plasmids can transfer DNA between gram-negative and gram-positive bacteria, and even from bacteria to yeast cells and plants. Theoretically, small changes in single genes could convert benign micro organisms into serious pathogens. Therefore, bacteria that carry promiscuous plasmids should be restricted to laboratory use only.
5. Possible Consequences
The potential harm associated with various genetically engineered micro-organisms is shown in the following diagram. Each number (1 through 12) represents the consequence of a particular combination of events and GMOs. 3 & 4 represent the intentional release of GMOs known to be harmful to the environment or to humans: e.g. in biological warfare or terrorism. 1 & 2 represent the inadvertent release of GMOs known to be harmful to the environment or to humans: e.g. in accidents at high-containment facilities that work with dangerous micro-organisms. 9 & 12 represent the intentional release of GMOs thought to be safe but which prove harmful, when the safety of organisms have been misjudged: e.g. micro-organisms that cause epidemics of cancer among the population. 10 & 12 represent the intentional release of GMOs which prove safe as expected: e.g. in oil recovery, mining, agriculture and pollution control. 6 & 8 represent the unintended release of GMOs which have no harmful consequences: e.g. in ordinary accidents with harmless micro-organisms. 5 & 7 represent the unintended release of GMOs thought to be safe but which prove harmful - the most unlikely possible consequence, because it requires both the occurrence of an accident and a misjudgment about the safety of the micro-organism.
6. Conclusion
As a result of the concerns described above, an environmental risk assessment must be carried out for any new project involved GMOs. Risk assessment is a process in which the probability or frequency of harm for a given hazard is estimated. An example of such a risk assessment was formulated by the 2012 iGEM team from Bettencourt, Paris. It must be carried out by the notifier, i.e. the person or body seeking consent for a proposed release, and it must address potential risks for human health and the environment. Where a specific risk or a degree of uncertainty exists, appropriate risk management techniques should be required to prevent adverse effects on people or the environment. In general, the accuracy of predictions of ecological, economic and social effects of releasing GMOs depends on the specific organism, the type of genetic information introduced, the particular environment into which it is released and the availability of detailed ecological information. Even so, the complexity of ecology is such that prediction will likely remain inexact. It is our hope that our self-destruct mechanism will minimize risks for the release of GMOs to the environment, and enable other projects to become reality.
Continue the journey: read about The Environmental Debate.
References
[1] G. Giddings, Tansley Review No. 99: The release of genetically engineered micro-organisms and viruses into the environment. New Phytol. 140, 173–184 (1998). [2] G. V. Dana, T. Kuiken, D. Rejeski and A. A. Snow, Four steps to avoid a synthetic-biology disaster. Nature 483, 29 (2012). [3] G. S. Sayler, S. Ripp, Field applications of genetically engineered microorganisms for bioremediation processes. Current Opinion in Biotech. 11, 286–289 (2000).
