Investigating the Possible Microbes for Bioremediation
By Sebastian Cuahutle Martinez, Global High School Fellow (Durham School of Technology ‘23)
Abstract
This paper was written to explore the possible microbes for bioremediation. Specifically, microbes could be genetically modified to eliminate gaseous pollutants without causing any subsequent harm to the environment or others. Literary sources were extracted from academic and peer-reviewed databases that focused on scientific journals. Additionally, an MD/PhD candidate was interviewed to bring valuable insight on the topic to this discussion. The most promising microbe for bioremediation would be an adeno-associated virus (AAV) which does not cause any harm, before genetically altering it, when introduced into the human body. The findings in this research paper are valuable as bioremediation is a relatively new scientific process that is currently being explored. Having this research can help young scientists and enthusiasts in bioremediation have a starting point in their learning journey. It should be noted that this research is only the beginning, and there are many more steps and research processes that can be taken to obtain more information on bioremediation.
Introduction
Bioremediation is a widely studied area of environmental biotechnology due to its potential to clean up polluted environments using natural biological processes. According to the Environmental Protection Agency, “Bioremediation is an engineered technology that modifies environmental conditions (physical, chemical, biochemical, or microbiological)” in order to destroy or reduce organic and inorganic contaminants in the environment using modified microbes of microorganisms. However, the efficiency of bioremediation is often limited by the low specificity and efficiency of natural biodegradative processes. Genetic engineering is a promising tool to overcome these limitations by developing genetically modified microbes (GMMs) or plants that can efficiently degrade pollutants. Genetic engineering has been applied to bioremediation and according to Das and Chandran, improving the degradative capabilities of pre-existing microbes allows for the construction of entirely new metabolic pathways in them and simultaneously optimizes environmental conditions (123). Moreover, the use of genetically engineered microbes for bioremediation has been explored, and it has been shown to be an effective approach for the removal of pollutants from the environment. This paper will explore possible microbes that can be genetically modified and aerosolized without affecting human health, consisting of research from previous studies and an interview with Rebecca Gibson, an MD-PhD candidate at Duke University School of Medicine, who will share her inputs, knowledge, and experience in biology and gene therapy.
Methods
The academic article “Microbial degradation of petroleum hydrocarbon contaminants: An overview” was extracted from the National Library of Medicine from the National Center for Biotechnology Information section. The phrase used in the search bar was “bioremediation.” Once results appeared, they were filtered out to only include articles published on or after the year 2010. The source type was then set to scholarly journals. A suitable article from Biotechnology Research International (2010) was then selected, analyzed, and read meticulously. Likewise, The academic article “Bench-Scale Evaluation of Aerosol Delivery for Biostimulation and Bioaugmentation in the Vadose Zone” was extracted from the ProQuests Biological Science Database… The phrase used in the search bar was “aerosolization AND bioremediation.” Once results appeared, they were filtered out to only include articles published on or after the year 2010. The source type was then set to scholarly journals and peer-reviewed. A suitable article from Biodegradation (201) was then selected, analyzed, and read carefully. Additionally, the information from the Environmental Protection Agency (EPA) was obtained from their official website. Finally, I conducted an interview with Rebecca Gibson, who is an MD-PhD candidate at the Duke University School of Medicine. Her aim is to become a pediatric geneticist. Obtaining information from an individual who works in the field of genetics is highly valuable due to their extensive education and laboratory experiences in handling genetically modified microbes. There is only so much information available on the internet, making such interviews essential for gaining insights from experts in the field.
Results
Research Findings
Researchers Hall, Richard J., et al. conducted a study that looked at how jet and ultrasonic aerosolizers could be used to deliver microbes for bioremediation of contaminated sites (clean up polluted soil) where trichloroethene (TCE), cDCE, and VC were used as model contaminants. Control tests were carried out to evaluate solute retention and mass loss in the absence of biological activity. An enclosed chamber, a horizontally oriented PVC pipe, and a vertically oriented tubing comprised the aerosol generation and delivery system. Ion chromatography was used to determine solute concentrations, and gas chromatography was used to determine mass present. The study looked at how aerosolization affected the activity of a bioaugmentation culture. They concluded that the ultrasonic aerosolization was significantly inhibiting. Direct jet aerosolization of the culture resulted in complete TCE dechlorination, whereas nutrient water delivery had no effect. Solutes were found to be retained within aerosol particles, and their concentration tended to increase, particularly during jet aerosolization due to a large volume of high-velocity gas. Because the humidity of the gas in the ultrasonic system was high, there was little evaporation. This study shows that modified microbes can be aerosolized at a high speed and retain contaminants in the air without setting it back out. They believe that in the future, this technique could be useful for cleaning up larger areas of pollution.
Interview Findings
Introducing new genetic material into an organism can be categorized into a permanent and non-permanent (diffusive) approach. The permanent approach involves inserting the gene of interest directly into the host organism or microbe genome, which is what CRISPR Cas9, a common gene-editing tool, does. The inserted gene will continue to express itself in the organism or microbe’s genome until it stops replicating. The non-permanent approach inserts wanted gene(s) into a plasmid, which will store its genetic material. This plasmid is then placed into the host-microbe. The plasmid is not inserted into the host microbes’ genome. The gene will express separately but concurrently to the host-microbe. However, the non-permanent introduction of genes does not last over a long period of time. Instead, the genes in the plasmid will diffuse as the host-microbe replicates.
A potential microbe for bioremediation is the Adeno-associated virus (AAV). AAV is a virus that does not harm human health when it is inserted into the body if it is not genetically modified. Therefore AVV is a highly promising candidate for bioremediation and is used by most who are experimenting with viral vector gene therapy. There are at least 12 serotypes of AAV, which are differentiated by the external structure of their capsid. AAV can be genetically modified by adding the gene of interest into the plasmid of the microbe. Since viruses attach to a host cell, the inserted gene is automatically replicated. When talking about AAV and gaseous pollutants, the gene of interest would be specific to different gaseous pollutants. Therefore, identifying genes that are associated with the specific gaseous pollutant and that have the ability to break it down is necessary. Once those genes are identified and inserted into the AAV plasmid the now genetically modified AAV will be tested for different dose concentrations and its efficacy. In attempting to eliminate gaseous pollutants, the efficacy would be evaluated in a testing zone by measuring the concentration of the pollutant both before and after introducing the genetically modified AAV (via aerosolization). Additionally, different concentrations of AAV would be tested to determine the optimal concentration-to-efficacy ratio. Ideally, there would be ants, flies, or mice in the testing zone, and would be monitored over a set amount of time to check for side effects or hazards the aerosol may have caused.
Discussion
The use of microbes for bioremediation is possible but one must follow a prolonged series of steps in order to obtain beneficial and effective results. Although this research is gathered as meticulously as possible and ensured for accuracy it still carries limitations. This information only helps set a fundamental element to research. The next steps include the development of the GMM identifying the needed genes to break down gaseous pollutants and making sure it is efficient. Additionally, clinical trials would be obligatory to ensure that the genetically modified AAV does not have any potential hazards or side effects on humans or the environment where it will be introduced. A possible trial would take place in a fixed setting where the air had a pre-measured amount of gaseous pollution with a person inside the fixed setting. The aerosolized modified AAV would then be released. The amount of gaseous pollutant would be measured again to check for a decline in the pollutant concentration and the person would then be monitored over a period of time to make sure the aerosol does not cause any health issues or side effects when introduced to the human body and system. Lastly, the FDA would need to ensure safety one last time before it gets approved. Although it’s a long process, the development of an eco-friendly, safe, and efficient aerosol to reduce pollution will have a significant impact in the long run. Especially now, when climate change and pollution are becoming more concerning than ever.
Sources
Das, S., and P. Chandran. “Microbial degradation of petroleum hydrocarbon contaminants: An overview.” Biotechnology Research International, vol. 2010, 2010, pp. 1–13.
Environmental Protection Agency. “Introduction to in Situ Bioremediation of Groundwater.” EPA, 10 Sept. 2021, https://www.epa.gov/remedytech/introduction-situ-bioremediation-groundwater.
Gibson, Rebecca. Zoom interview with MD/PhD candidate. 22 March. 2023.
Hall, Richard J., et al. “Bench-Scale Evaluation of Aerosol Delivery for Biostimulation and Bioaugmentation in the Vadose Zone.” Biodegradation, vol. 26, no. 2, 2015, pp. 91–103. ProQuest, https://login.proxy055.nclive.org/login?url=https://www.proquest.com/scholarly-journals/bench-scale-evaluation-aerosol-delivery/docview/1669579041/se-2, doi:https://doi.org/10.1007/s10532-015-9718-5.
