Team:Tongji China/tags/v0.2/json/description.json
{
"header": "Contents
Biosynthesis
the future of indigo
", "content": "Inspiration and Motivation
At the beginning of this iGEM season, our team noticed a news reporting that a fire case happened in an indigo factory. This arose our concern on indigo synthesis.
After we studied the situation of the indigo industry in-depth, we found that:
Indigo is commonly used to dye denim. Textile fabrics with denim as raw materials are widely sought after all over the world, and their special texture and fading characteristics after washing are the reasons why people choose denim clothing. The global denim market grew 8.9% between 2013 and 2018, from $52.6 billion to $57.3 billion, according to a global market review published by Just Style. It is expected to reach nearly $60 billion by 2023. This figure shows that jeans have a large market share in the world and are on the rise.
With the growing market of denim, environment problems of the indigo industry become more and more serious.
However, the production of denim products has environmental problems that we can not ignore.
1. Synthesis of indigo
At present, the vast majority of indigo dyes are synthesized from petrochemical products, in which dangerous chemicals such as hydrogen cyanide, aniline, and potassium hydroxide are used.
China is the world’s largest indigo supplier; 98 % of indigo is produced in China. Therefore, we are facing more problems with the environment caused by the indigo industry.
In China, environmental policies are very strict. To meet the requirements of these policies, enterprises have to:
Establish a waste treatment system of their own
Pay for the downstream waste treatment
Keep their waste emissions within the required amount
To meet these requirements, enterprises need to expand their factories, or they have to reduce their production to make room for waste treatment systems. They should limit their production because of the pollution discharge limit.
Besides, chemical synthesis of indigo uses aniline as the raw material, which is hard to remove from the final product. This restricts the use of chem-indigo in medicine and food.
2. The printing and dyeing process of indigo
Because of the insolubility of indigo itself, it needs to be reduced before dyeing. In this treatment process, the use of chemicals such as sodium disulfite, potassium hydroxide, and other chemicals also do great harm to the environment.
In Guangdong Province, China, a large number of garment processing plants have gathered. Among them, Xintang Town is known as the \"cowboy town\" because of the high concentration of the jeans industry. Every day, Xintang produces millions of pairs of jeans, where more than 60% of China's denim products are produced. The high concentration of production magnifies the environmental pollution of the denim industry. In the process of textile processing, a large number of sewage containing toxic and harmful substances will be produced, and this sewage often enters the river without strict treatment. The river in Xintang Town is often filled with sewage of various colors. The air often has a pungent stench. A large amount of sewage is not strictly treated along the river and eventually flows into the sea. At the same time, it is not difficult to imagine that the health of workers working in such an environment will also be seriously threatened.
There is a large demand for denim products. Based on this, we want to realize the production process of environment-friendly denim products.
About our project
Foundation
Most of the previous works concerned with the production of indigo, which was what we tried to do in the first place. Based on previous work, we designed a pathway to synthesis indigo in engineered E. coli.
However, indigo is insoluble, and it should be reduced before dyeing. This is the key resource of pollution. Producing bio-indigo will only solve the problem of indigo producer, not the dyeing & finishing enterprises which are in a more serious situation of pollution.
Luckily, during our research, we found that in 2013, team Berkeley put forward a pathway of glycosylating indoxyl using a plant-derived glucosyltransferase (BBa_K1131006), a precursor of indigo, to form indican to avoid the reduction of indigo when it is used to dye, which greatly reduces the production of sewage during dyeing. Some of their team members continued their research and found a new UDP-glycosyltransferase[1]. Their work is very enlightening for us.
Our Goals
Verify the function of bacterial flavin-containing monooxydase (bFMO) and UDP-glycosyltransferase PtUGT1
These are two of the most important steps in indigo biosynthesis. We need at least bFMO to produce indigo and convince our potential users.
Upregulate the Shikimate pathway to get higher tryptophan production, reduce the addition of tryptophan
Try to collect bio-indigo samples for our cooperator, Jiangsu Taifeng Chemical Co. Ltd, to test their dyeing ability
Overexpress tnaA gene to resist the inhibition of glucose, therefore making it more viable for the enterprises
Overexpress zwf gene to make the NADPH level higher, therefore promotes the pathway
The reaction catalyzed by bFMO needs NADPH, higher NADPH level will promote it.
Tryptophan is more expensive than indigo; less use of tryptophan will reduce the cost of bio-indigo/indican.
The tna operon is repressed by glucose, which is a component of molasses, a regularly used carbon source in the fermentation industry.
Details about the pathway design, see our project <a href=\"design.html\">design</a>.
Step in Step...
We conceive that applying indican as a dye is still too hard, for it needs new production lines, which is unrealistic. For the first step, we will try to lower the cost of bio-indigo, for it is easier to be accepted by dyeing & finishing enterprises.
In the long-term, indican still seems to be the best solution. So it is necessary to establish a new dyeing process using indican.
First, we will start by producing indigo. Then, let us explore the limit of bio-indigo/indican.
Overall, our project provides a better long-term solution in the indigo synthesis, and it is more viable for industry.
}