Description

Description

Background




Indoor air pollution can lead to non-communicable diseases such as stroke, ischemic heart disease, chronic obstructive pulmonary disease, and lung cancer. Women and children who are responsible for cooking and collecting firewood bear the heaviest burden of the health consequences of using polluting fuels and practices at home. According to the World Health Organization, around 2.4 billion people (about one-third of the global population) use open fires or traditional stoves with inefficient combustion of solid fuels such as kerosene, biomass (wood, animal dung, and crop waste), and coal, causing harmful indoor air pollution (WHO, 2021).

Among the population who die due to indoor air pollution (WHO, 2021):

32% die from ischemic heart disease, accounting for 12% of total deaths from ischemic heart disease. Over 1 million people die prematurely each year due to indoor air pollution.

23% die from stroke, with 12% of total stroke deaths caused by indoor air pollution from daily exposure to solid fuels and kerosene used for cooking at home.

21% die from lower respiratory infections: indoor air pollution increases the risk of lower respiratory infections in children by almost doubling it. Among children under five who die from pneumonia, 44% die due to indoor air pollution. Indoor air pollution is a risk factor for acute lower respiratory infections in adults, causing 22% of adult pneumonia deaths.

19% die from chronic obstructive pulmonary disease: in low- and middle-income countries, 23% of adult deaths from chronic obstructive pulmonary disease are caused by indoor air pollution.

6% die from lung cancer: approximately 11% of adult deaths from lung cancer are caused by indoor air pollution from exposure to carcinogens in solid fuels such as kerosene or wood, charcoal, and coal used for cooking.





In 2019, indoor air pollution was estimated to cause a loss of 86 million healthy life years, with the greatest burden falling on women in low- and middle-income countries (WHO, 2021). Nearly half of the deaths of children under five due to lower respiratory infections are caused by inhaling indoor air pollution particles. There is also evidence linking indoor air pollution to low birth weight, tuberculosis, cataracts, nasopharyngeal cancer, and laryngeal cancer. Therefore, indoor air pollution is a serious and urgent global issue (WHO, 2021).

In recent years, due to the impact of the pandemic, most people stay indoors. Once indoor air pollution problems occur, they will have serious consequences, making the already scarce public health resources even more tense. During the pandemic, our university built a new teaching building, and another research building is under construction. The new decoration and population density in classrooms have raised concerns about indoor air pollution. In response to student appeals, the university hired a professional indoor air purification company to treat the air in the new teaching building. However, traditional air purification methods are expensive, cannot be used repeatedly in the long term, and are not conducive to ecological protection. Therefore, our team are trying to use synthetic biology to find new green and efficient solutions to the problem of indoor air pollution.

Among the various indoor air pollutants, formaldehyde and hydrogen sulfide are widely recognized as gases with high levels of harm and difficulty in degradation.

Formaldehyde is a toxic and harmful gas. Long-term exposure can cause symptoms such as sore throat, headache, and fatigue, and serious exposure can lead to diseases such as nasopharyngeal cancer and leukemia.

Hydrogen sulfide is a highly toxic gas. Long-term exposure can cause damage to the respiratory system, central nervous system, eyes, skin, and other organs. Inhalation of high concentrations of hydrogen sulfide can lead to respiratory distress, pulmonary edema, suffocation, and other serious consequences. Long-term exposure to high concentrations of hydrogen sulfide can also cause damage to the immune system, cancer, and other serious consequences.

SUSTech-OCE is dedicated to using a green and sustainable co-cultivation system of algae and bacteria to remove formaldehyde and hydrogen sulfide, which are difficult to degrade naturally, from indoor air pollutants. This aims to raise public awareness of indoor air pollution and promote a green, environmentally-friendly, and healthy lifestyle.

---




Current Solutions



• Natural Ventilation:

Relies on the natural airflow patterns in the environment to achieve indoor air circulation and renewal, mainly based on temperature difference, pressure difference, and wind force. The disadvantages are that it is easily affected by the structure of the building and the weather, and cannot achieve thorough removal of pollutants.



• Mechanical Ventilation:

Uses fans to force airflow to achieve indoor air renewal. The disadvantages are that it requires a large amount of energy consumption, which will increase the energy consumption cost of the building; it may bring noise, affecting the comfort of the occupants; and it cannot achieve thorough removal of pollutants.



• Activated Carbon Adsorption:

Activated carbon is a highly active adsorbent, and its adsorption principle is mainly based on three mechanisms: physical adsorption, chemical adsorption, and electrostatic adsorption. The disadvantages are that the adsorbent needs to be replaced or regenerated after reaching saturation, which will bring certain costs; the adsorbent needs to be processed after use, otherwise it may cause pollution to the environment, and it cannot achieve thorough removal of pollutants.



• Air Purificant:

The active components in air purificants can chemically react with pollutants in the air, causing oxidation, reduction, acid-base neutralization, and other reactions, and converting them into harmless substances, such as water and carbon dioxide. The disadvantages are that the air purificant itself may not be environmentally friendly, as well as its production process; it cannot continuously purify the air and can only be effective for a period of time.

---




Our Idea




Current gas purification products on the market cannot simultaneously meet the three characteristics of continuous and thorough removal of pollutants, environmental friendliness, and low energy consumption. We hope to use genetically edited E. coli to absorb and process these pollutants with the ultimate release of non-toxic gases, mainly carbon dioxide, which can emit fluorescence to give people an intuitive understanding of the degree of pollution. In addition, we introduce cyanobacteria, a photosynthetic autotroph, into the container where E. coli grows, which can absorb carbon dioxide and release oxygen while providing the necessary energy and resources for E. coli.

We hope that this purification system can achieve sustainable gas purification within a certain temperature range, energy-saving, and only requires a certain amount of light to operate. It can catalyze the oxidation of formaldehyde and hydrogen sulfide, and ultimately transform them into carbon dioxide, sulfates, etc., achieving thorough removal of pollutant gases and also releasing oxygen. We plan to use a stylish container to house this co-culture system.

---




Our Solution



• Regarding formaldehyde:

Detection and Indication: We will introduce formaldehyde-induced promoter and fluorescent protein-related genes into E. coli BL21. In the absence of formaldehyde, FrmR protein binds to the PfrmR promoter region, preventing transcription. In the presence of formaldehyde, FrmR reacts with formaldehyde, causing a conformational change that leads to dissociation from the promoter, allowing normal expression of the downstream fluorescent protein gene.

Treatment: We will introduce formaldehyde dehydrogenase and formate dehydrogenase-related genes into E. coli BL21, allowing the expression of this pathway when the formaldehyde concentration reaches a certain threshold, ultimately oxidizing formaldehyde into carbon dioxide for absorption and processing.

• Regarding hydrogen sulfide:

Detection and Indication: We will introduce Sqr (sulfide quinone oxidoreductase) protein, sqrR inhibitor protein, and fluorescent protein-related genes into E. coli BL21. Sqr protein can oxidize negative divalent sulfide to elemental sulfur. Elemental sulfur can interact with the sqrR protein in the promoter region to activate the expression pathway of the fluorescent protein, indicating whether the hydrogen sulfide concentration exceeds the standard.

Treatment: We will introduce Sqr (sulfide quinone oxidoreductase) and PDO (peroxide dismutase) related genes to E. coli BL21, allowing the expression of this pathway when the hydrogen sulfide concentration reaches a certain threshold, ultimately oxidizing hydrogen sulfide into sulfate.