Team:RUM-UPRM/Description
Project Description
Our Problem
Vieques, an Environmental Crisis
In the 1940s, two-thirds of Vieques, an island-municipality of Puerto Rico, was used as a military training site by the U.S. Navy. During this period, the lands and waters of Vieques were used as bombing ranges and military practices, disturbing the Island. After years of on-going protests, the Navy finally abandoned Vieques in 2003 leaving behind an array of contamination; including heavy metals and organic compounds.[1,2] These events led to Vieques being one of the most contaminated places in the Caribbean.
The contamination left behind has been a major disturbance to the ecosystem and its biodiversity. Species of flora and fauna have presented bioaccumulation of heavy metals, therefore, affecting the local economy, which relies significantly on its fertile soils and fishing. Additionally, the presence of these contaminants poses a threat to public health, increasing the risk of long-term diseases such as cancer.[3] Compared to the main Island, Vieques presents a higher rate of cases of cancer.[4]
Currently, there are initiatives to clean the affected areas of Vieques. The agency that oversees this is the U.S. Environmental Protection Agency (EPA). Their plan has been to restrict access to the contaminated lands and remove bombs by open-air denotation. The problem with these techniques is that they are time-consuming and open-air detonation results in the uncontrolled release of toxic contaminants to the environment, which only aggravates the problem. Around 4,000 of 10,000 acres of surface contaminants have been cleaned but bodies of water and underground surfaces, which are also contaminated, have not been included in the cleaning plans.[5]
One of the most contaminated bodies of water in Vieques is the Anones Lagoon. It is listed in the EPA’s Superfund National Priorities List indicating that the contamination poses a threat to human health and environmental risks.[6] Moreover, this lagoon is directly connected to the Caribbean Sea, meaning the water’s current can carry the contaminants to open water.
Why Mercury and RDX?
Mercury is a toxic element able to bioaccumulate in different species of fish, crustaceans, and plants.[7] Species that feed on these organisms prolong the accumulation and magnification of the effects of mercury. High concentrations of this heavy metal can disperse in an open environment through different biotic and abiotic factors. Mercury can have many negative effects on the human health, including muscle weakness, and can cross placental barriers in pregnant women which can cause neurophysiological problems to the fetus.[3]
As well as Mercury’s incidence as a contaminant, RDX, a nitro-explosive, is a synthetic white crystalline solid used extensively by the U.S. army in bombs.[8] It is considered to be a possible carcinogen for humans and animals. It has become an extensive global pollutant, and the demand for military explosives means that RDX will continue to be manufactured and used for the foreseeable future.[9] In relation to its environmental effects, RDX has shown migration to groundwater due to low adsorption of soil, affecting groundwater, as well as open waters.[10]In addition, RDX has a slow degradation rate in water, and can bioaccumulate in plants, including aquatic vegetative specimens.[10] Aside from being a possible carcinogen, RDX can affect the nervous system, causing seizures.[11,12] RDX can also cause nausea, vomiting, eye, and skin irritation, fatigue, tremor, and insomnia. [13,14]
The Chassis
Pseudomonas putida
Pseudomonas putida is considered one of the most versatile bacterial strains since it possesses several distinctive characteristics that are required in order to create a viable prototype. This bacterium is Gram-negative and aerobic, requiring oxygen for its metabolism. This saprotrophic bacteria is rod-shaped and measures between 0.5 and 0.8μm. A favorable element that this bacterium provides is the many plasmids it contains, which is a great attribute to apply in synthetic biology mechanisms. It also has the ability to emit green fluorescent pigments.[15]
In order to survive, P. putida requires a temperature between 25-30°C and a neutral pH of 6-8. It is important to highlight that this bacterium can be considered a human pathogen; however, it’s naturally found in soil and is non-pathogenic to plants or animals. Another significant characteristic is the tolerance to environments with metal contamination and the ability to increase resistance to heat and saline stressors through its filamentous phenotype. These characteristics make this organism of great interest for bioremediation and serves as a biosensor for the detection of a variety of pollutants, which we found to be a determining factor in order to apply it to our genetic construct that focuses on the detection and biodegradation of contaminants like mercury and RDX. [15]
Our Solution
Mer-Nite to the Rescue
Synthetic Biology has helped provide many solutions for a wide variety of the world's current environmental problems. We propose to implement the use of this emergent field to mediate contamination caused by military practices in Anones Lagoon in Vieques, Puerto Rico. Our project, Mer-Nite to the Rescue, focuses on the bioremediation of mercury and biodegradation of the organic explosive compound RDX to remove these pollutants in the Anones Lagoon. To achieve this, our prototype consists of a construct bacterium Pseudomona putida that will be contained within a bioreactor. The genetically modified bacteria will be able to detect, absorb, and biodegrade or bioremediate the contaminants. Meanwhile, the hardware shall work as a water filter device that will draw in the contaminated water into the chamber with our construct bacterium and release the water free of mercury and RDX.
References
[1] Dávila-Santiago, L., DeLeón-Rodriguez, N., LaSanta-Pagán, K., Hatt, J. K., Kurt, Z., Massol-Deyá, A., & Konstantinidis, K. T. (n.d.). Microbial Diversity in a Military Impacted Lagoon (Vieques, Puerto Rico) as Revealed by Metagenomics. BioRxiv. doi:10.1101/389379
[2] Quintero, A. C. (2008). Diversity and Microbial Community Structure at a Former Military Ranges in Vieques (Puerto Rico).
[3]Ortiz-Roque, C., & Lopez-Rivera, Y. (2004). Mercury contamination in reproductive age women in a Caribbean island: Vieques. J Epidemiol Community Health, 4(58), 756-757. doi:10.1136/jech.2003.019224
[4] Public health assessment Isla de Vieques Bombing Range, Vieques, PR. (2003) U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry. https://www.atsdr.cdc.gov/HAC/PHA/reports/isladevieques_02072003pr/index.html
[5] Citations: Civilian exposure to munitions-specific carcinogens and resulting cancer risks for civilians on the Puerto Rican island of Vieques following military exercises from 1947 to 1998. (2017). Global Security: Health, Science and Policy. https://www.tandfonline.com/doi/citedby/10.1080/23779497.2017.1369358?scroll=top&needAccess=true
[6] Atlantic Fleet Weapons Training Area-Vieques, Vieques, Puerto Rico. EPA’s Superfund National Priorities List: Site Listing Narrative. https://semspub.epa.gov/work/02/363533.pdf
[7] Massol-Deyá, A., Pérez, D., Pérez, E., Berrios, M., & Díaz, E. (2005). Trace Elements Analysis in Forage Samples from a US Navy Bombing Range (Vieques, Puerto Rico). International Journal of Environmental Research and Public Health, 2(2), 263-266.
[8] Environmentalrestoration.wiki. (2020). Retrieved 27 October 2020, from http://www.environmentalrestoration.wiki/images/f/f8/USEPA-2014-RDX_Technical_fact_sheet_contaminant_final_Report.pdf.
[9] Rylott, E. L., Jackson, R. G., Sabbadin, F., Seth-Smith, H. M., Edwards, J., Chong, C. S.,Bruce, N. C. (2011). The explosive-degrading cytochrome P450 XplA: Biochemistry, structural features and prospects for bioremediation. Biochimica Et Biophysica Acta (BBA) - Proteins and Proteomics, 1814(1), 230-236. doi:10.1016/j.bbapap.2010.07.004
[10]Clausen, J., Korte, N., Dodson, M., Robb, J., & Rieven, S. (2006). Conceptual Model for the Transport of Energetic Residues from Surface Soil to Groundwater by Range Activities. https://apps.dtic.mil/dtic/tr/fulltext/u2/a472270.pdf.
[11] National Center for Biotechnology Information (2020). PubChem Compound Summary for CID 8490, Cyclonite. Retrieved October 27, 2020 from https://pubchem.ncbi.nlm.nih.gov/compound/Cyclonite.
[12]Ketel WB, Hughes JR. Toxic encephalopathy with seizures secondary to ingestion of composition C-4. A clinical and electroencephalographic study. Neurology. 1972 Aug;22(8):871-6. doi: 10.1212/wnl.22.8.870. PMID: 4673417.
[13]CDC - NIOSH Pocket Guide to Chemical Hazards - Cyclonite. (2020). https://www.cdc.gov/niosh/npg/npgd0169.html
[14]National Center for Biotechnology Information (2020). PubChem Compound Summary for CID 8490, Cyclonite. Retrieved October 27, 2020 from https://pubchem.ncbi.nlm.nih.gov/compound/Cyclonite.
[15]Becerra Mejía, C. (2007). Optimización de un medio de cultivo para la producción de biomasa de la cepa Pseudomonas putida UA 44 aislada del suelo bananero de Uraba –Antioquia. Universidad EAFIT, 21-22. Retrieved 18 October 2020, from https://repository.eafit.edu.co/bitstream/handle/10784/402/CamiloAndres_BecerraMejia_2007.pdf?sequence=1&isAllowed=y.
[16] Vieques Environmental Restoration News ( 2020). Naval Facilities Engineering Command. https://www.navfac.navy.mil/content/dam/navfac/Environmental/PDFs/env_restoration/vieques/AugSep_2020_Flyer.pdf
[17]United States Environmental Protection Agency (EPA). 2017. Technical Fact Sheet Hexahydro-1,3,5-trinitro1,3,5-triazine (RDX). https://www.epa.gov/fedfac/technical-fact-sheet-hexahydro-135-trinitro-135-triazine-rdx