Overview

Formaldehyde (HCHO), a major indoor air pollutant, attracts worldwide attention because the exposure to formaldehyde is known to cause irritation, allergic asthma and neurasthenia, as well as to induce carcinogenicity and carcinogenesis. Since synthetic resins, including urea-formaldehyde, phenol-formaldehyde and melamine-formaldehyde which are widely used in buildings and furnishings, newly built or remodeled residences are often found to release high levels of indoor formaldehyde from wood-based products, wall coverings, rubber, paint, adhesives, lubricants, cosmetics, electronic equipment, and combustion. The surveys in China during the period of 2002–2004 revealed that indoor formaldehyde levels in more than 69.4% of all new or newly remodeled houses exceeded the national standard of China( ).

Formaldehyde removal from indoor air conduces to decrease the health risk for inhabitants.Therefore, the mitigation of formaldehyde is a significant practice. Purification technologies commonly used for indoor air pollution control include adsorption, chemisorption, photo catalytic oxidization, plasma and thermal catalytic oxidization.However, the removal of indoor formaldehyde is still a challenging problem due to the low rate, byproduct formation and low efficiency of the previous mentioned methods.There are also more natural ways to remove formaldehyde,such as phytoremediation. Phytoremediation, defined as the use of plants to remove toxins from the air, water and soil, has been proposed as a cost efficient and effectiveway to improve indoor air quality.

As we all know that various plants can remove formaldehyde from indoor air by means of the uptake and metabolism. It has been proved that formaldehyde as a central intermediate of photosynthetic carbon dioxide fixation in green plants can be removed by forming S-formylglutathione . Thus, exogenous formaldehyde absorbed by plant can be metabolized in plant tissues. Besides, plant roots and soil microorganisms may remove air pollutants which enter into soil or water.

In this project, our objective is to further increase plant formaldehyde uptake and metabolism ability using synthetic biology methods. We find some genes encoding key enzymes related to formaldehyde metabolic pathways from microorganism. They are 3-hexulose-6-phosphate(HPS), 6-phospho-3-hexuloisomerase(PHI), formaldehyde dehydrogenase(FALDH) and formate-dehydrogenase(FDH). These genes are inserted into plants and will work to promote formaldehyde metabolism. For security reasons, we also add gene AdCP into our project because of its capability to lead to pollen abortion. At the same time, chloroplast transformation is taken into consideration to decrease the probability of gene flow.