Aromatherapy can be used as a complementary therapy to relieve adolescent stress. However, traditional methods to produce these aromatic substances, such as terpenes, are often both complicated and polluting. Therefore, we attempted to find a bioengineering way to produce these aroma substances that can replace traditional processes and can be directly used in daily life. Through research and discussion within our team and with experts, we finally decided to use cyanobacteria are our chassis. Cyanobacteria can use photosynthesis as a source of energy and carbon, and it has a preexisting MEP pathway for the synthesis of terpene molecules. After successful engineering of cyanobacteria, we are committed to developing our scent-producing cyanobacteria into scent generators that can meet the daily needs of people. We have designed several bioreactors that can support the living and scent production of cyanobacteria. We have also designed suicide switches inside the cyanobacteria which can prevent the biohazards of the engineered cyanobacteria.
Stress is a physiological response defined as a state of worry or mental tension caused by a difficult situation, or otherwise known as stressors [1]. There are benefits to moderate levels of stress, such as staying more focused on tasks and having more motivation. This is due to stressors activating processes along the hypothalamic-pituitary-adrenocortical (HPA) axis, which are designed to increased energy and vigilance to confront the threat posed by stressors. However, excessive stress and overstimulation of the HPA axis can lead to a number of negative mental and physical health consequences [2]. If the individual is unable to cope with stressors, the physiological reaction will not be effectively moderated and will lead to a high allostatic load, or the cumulative burden of chronic stress on regulatory systems and it is associated with negative health outcomes [3]. Constant stress experienced over a prolonged period of time contributes to severe health issues, such as anxiety and depression. As reported by the WHO, around 20% of children and adolescents worldwide suffer from mental health conditions [4]. Aside from mental health issues, experience of chronic stress causes damage to the body and brain resulting in noncommunicable diseases (NCDs), which are the leading cause of death worldwide [5]. According to the WHO, NCDs kill 41 million people each year [6].
Stress is particularly problematic among adolescents, whose brains are undergoing rapid changes and very prone to the influence of external factors. Adolescence is a critical stage of biological and cognitive development defined as the transition from childhood to adulthood. Under this stage, individuals experience drastic changes in all aspects of their lives, which makes them especially vulnerable. Exposure to substantial stressors in adolescence is shown to induce hippocampus damage and leads to a higher possibility of the emergence of psychosis later in adulthood [7]. Adolescent stress is on the rise in recent years. There are a number of stressors unique to adolescence, which includes adult expectations, social relationships, school pressure etc. Most commonly, adolescence stressors come from unavoidable external factors such as those related to academics. Nevertheless, adolescent stress as a health issue is often overlooked and they are not given sufficient support to cope with stress [8][9].
In addition to traditional stress management techniques such as meditation and exercise, aromatherapy is also found to be effective in reducing stress and promoting relaxation. Aromatherapy is a natural treatment using fragrances and has been practiced since the beginning of recorded history. It involves using essential oils obtained mostly through plant extractions and chemical synthesis. Many of the popular fragrances come from scarce plants, such as sandalwood essential oils. Olfactory aromatherapy, the inhalation of fragrances, is the focus of this project. In comparison to traditional approaches, aromatherapy is a much more practical relaxation method as it does not require any additional time commitment or effort. The sense of smell is our most primitive sense and is considered the strongest and quickest memory inducer due to the close connection of the olfactory bulb to the hippocampus and amygdala. Fragrance compounds taken in by respiration cause indirect psychological and physiological effects by activating olfactory memory [10]. It also results in the release of endorphins, which help reduce stress and uplift mood. This allows olfactory aromatherapy to result in enhanced emotional wellness, calmness, and relaxation of the body [11].
Terpenes are a large family of hydrocarbons that are responsible for the way most plants smell. They are categorized based on the number of five-carbon units. The fragrance molecules we aim to produce are in the categories of monoterpenes (C10) and sesquiterpenes (C15).
α-pinene, is an organic chemical with formula of C10H16, and is a colorless, slightly water-soluble compound with a market value of about 130 RMB per Kilogram. It is commonly used in manufacturing of fragrances, such as Terpinol, Linalool, and others. It can also be used in industrial lubricant. In aromatherapy, α-pinene is mainly used to relieve chronic pain and stress, but as an antioxidant it can also be used to reduce inflammatory problems like asthma and bronchitis. It can also reduce the risk of developing chronic diseases like Alzheimers and Parkinsons disease. There are currently two major ways of procuring α-pinene: Chemical Synthesis and Natural Extraction. Both, though, have major disadvantages that need solving: Chemical Synthesis, which suffers from low rates of Isomerization and a hefty energy bill, creates byproducts that if handled incorrectly could be harmful to the environment and our bodies (for example, applying badly processed α-Pinene via Aromatherapy). Natural Extraction, on the other hand, requires heaps of biomass for only a small amount of α-Pinene, causing mass deforestation and Ecosystem destabilization in pursuit of said biomass.
Beta-pinene is a natural monoterpene found in plants, renowned for its health benefits, including anti-inflammatory and stress-relieving properties. One study at the University of Wisconsin proved that, through using Synechococcus sp. PCC 7002, a fast-growing cyanobacterium, beta pinene can be manufactured by supplementing the methyl-erathritol-phosphate (MEP) pathway with two other enzymes. This means that it is very possible to replicate this in Syn. PCC 6803, our chassis. Traditional production methods, involving tree oil extraction, are detrimental to the environment.
Limonene-S (LIMS) is a lesser-known limonene compound than Limonene-R, is an organic chemical with formula of C10H16, and is a colorless, slightly water soluble compound with a market value of about 360 RMB per Kilogram. It is a very versatile molecule, being used in many ways, including to help inhibit the spread of colon cancer cells, used to create Carvone and Tupertine, and various other uses in food flavoring, solvents, wetting and cosmetics, leading to its large market value of around 330 million USD. It is used as an anti-stress and anti-anxiety agent in aromatherapy.
There are two main types of fragrances currently available in the market, which are natural and synthetic fragrances. Natural fragrances are those extracted from trees, plants, and animals through pressing or distillation. This approach is characterized by drawbacks such as prolonged process of extraction, weak concentrations of desired compounds and natural factors makes it difficult to recreate a fragrance. Additionally, extracting natural fragrances requires large quantities of raw material, which makes this method non-eco-friendly. Many essential oils come from vulnerable plant species, such as sandalwood. In contrast, synthetic fragrances do not exhibit some of the above problems. However, synthetic fragrances pose a number of threats to the environment and human health, due to that they are derived from petroleum by-products. Not only does the production process generate lots of pollution, but the final products containing these synthetic fragrances have also been found to contribute to air pollution. The NOAA reports the number of chemical vapors emitted into the atmosphere by scented products and vehicles are roughly the same [12]. This is problematic because pollutants emitted by fragrances can cause several health issues in humans, such as respiratory disorders, cardiovascular disease, and cancer [13]. Altogether, these factors demonstrate that current fragrance production methods are unsustainable.
Taking into consideration the above-mentioned serious impacts of stress on both individuals and broader societal health, we have realized that it is a severe problem that must be solved immediately. We strongly believe that aromatherapy is the go-to solution for this problem due to its inherent accessibility and established therapeutic benefits. However, current methods of fragrance production bear significant shortcomings. Therefore, we propose to produce fragrances through the means of synthetic biology. We aim to metabolic engineer cyanobacteria, Synechocystis sp. PCC 6803, to enable them to produce fragrances wherever there is light, carbon dioxide, and nutrients. By using cyanobacteria, we desire to reduce the industry's carbon footprints and create an environmentally friendly, sustainable agricultural practice of producing high value biomass. By cultivating cyanobacteria, we are cultivating a future where fragrances emanate from eco-conscious sources, thus promoting ecological equilibrium and reducing the stain on finite resources.
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[1] Stress. 17 June 2022, Web.
[2] Gulliams, Thomas. "Chronic Stress and the HPA Axis: Clinical Assessment and Therapeutic Considerations." standard_v_9.2_hpa_axis.pdf (pointinstitute.org)
[3] B.S. McEwen. "Stress: Homeostasis, Rheostasis, Reactive Scope, Allostasis and Allostatic Load." , Stress: Homeostasis, Rheostasis, Reactive Scope, Allostasis and Allostatic Load - ScienceDirect.
[4] World Health Organization: WHO. "Mental Health." Mental health (who.int)
[5] Fricchione, Gregory L. "The Challenge of Stress-Related Non-Communicable Diseases." Medical Science Monitor Basic Research, vol. 24, International Scientific Information Inc., June 2018, pp. 93-95, doi:10.12659/msmbr.911473.
[6] SDG Target 3.4 Non-communicable Diseases and Mental Health. 16 Sept. 2023, Web.
[7] Gomes, Felipe V., and Anthony A. Grace. "Adolescent Stress as a Driving Factor for Schizophrenia Development—A Basic Science Perspective." Schizophrenia Bulletin, vol. 43, no. 3, Oxford UP, Apr. 2017, pp. 486-89, doi:10.1093/schbul/sbx033.
[8] Magwa Simuforosa. "Stress and adolescent development." Microsoft Word - 240913860 Simuforosa (psu.edu)
[9] Lisa Kort-Butler. The Stress Mechanisms of Adolescent Physical, Mental, and Behavioral Health. The Stress Mechanisms of Adolescent Physical, Mental, and Behavioral Health (unl.edu)
[10] Sowndhararajan, Kandhasamy, and Songmun Kim. "Influence of Fragrances on Human Psychophysiological Activity: With Special Reference to Human Electroencephalographic Response." Scientia Pharmaceutica, vol. 84, no. 4, Österreichische Apotheker-Verlagsgesellschaft m. b. H., Nov. 2016, pp. 724-51, doi:10.3390/scipharm84040724.
[11] Vivek Dave, "AROMATHERAPY FOR STRESS RELIVE", Microsoft Word - Vivek Dave 2 (psu.edu)
[12] "Those Scented Products You Love? NOAA Study Finds They Can Cause Air Pollution." National Oceanic and Atmospheric Administration, 15 Feb. 2018, Web.
[13] Kazemi, Zeinab, et al. "Evaluation of Pollutants in Perfumes, Colognes and Health Effects on the Consumer: A Systematic Review." Journal of Environmental Health Science & Engineering, vol. 20, no. 1, Springer International Publishing, Feb. 2022, pp. 589-98, doi:10.1007/s40201-021-00783-x.
Tom Nikkola. “Alpha-Pinene: Powerful Effects of an Essential Oil Compound on Health.” Tom Nikkola, 29 May 2023, Web. Accessed 01 Oct. 2023.
“Alpha Pinene Price, 2023 Alpha Pinene Price Manufacturers & Suppliers.” Made, Web.
“Α-Pinene.” α-Pinene, National Institute of Standards and Technology, webbook. Web.
Sobel, Ashley. “Limonene: Uses, Benefits, Side Effects, and Dosage.” Healthline, Healthline Media, 13 July 2023, Web.
“(S)-(-)-Limonene, 97%, Thermo Scientific Chemicals | Fisher Scientific.” Web. Accessed 1 Oct. 2023.
“Limonene.” American Chemical Society, Web.
Rolf, Jascha, et al. “A Gram-Scale Limonene Production Process with Engineered Escherichia Coli.” Molecules, vol. 25, no. 8, 18 Apr. 2020, p. 1881, Web.
“Love Sandalwood? It’s Facing Extinction. Here’s Why.” Australian Geographic, 8 Oct. 2021, Web. Accessed 1 Oct. 2023.
“Opoponax Essential Oil Uses and Benefits.” AromaWeb, Web.
Yeo, Syn Kok, et al. “β-Bisabolene, a Sesquiterpene from the Essential Oil Extract of Opoponax (Commiphora Guidottii ), Exhibits Cytotoxicity in Breast Cancer Cell Lines.” Phytotherapy Research, vol. 30, no. 3, 15 Dec. 2015, pp. 418–425, Web. Accessed 12 Apr. 2021.