Our project was inspired by an arsenic contamination case back in 2013, the original intention of our project is to design a convenient detection and treatment system for heavy metal arsenic. In order to better define the application direction of our project, we have carried out a number of human practice activities, including questionnaire survey, expert interviews, and field research. These activities feedback to our project, let us adjust the direction of the project, more focus on arsenic treatment rather than detection. Furthermore, we optimized the bioremediation system for arsenic treatment.
Begin
We start our research of Arsenic from a piece of news:On October 2013, nine villagers in Dawang Town, Yangxin County, Huangshi City, Hubei Province started to have symptoms like anorexia, limb weakness, dizziness, and palpitation, among which two elders even suffer from breathing problems, convulsion, and coma. Diagnosed by Wuhan occupational disease hospital, they were actually poisoned by Arsenic.Therefore, we hope to know more about the damage of Arsenic pollution towards mankind and environment.
Interview with expert
We want to use synthetic biological methods to transform engineering bacteria to detect arsenic in different concentrations in water pollution conveniently. Then, we contacted Ms. Li of Wuhan College of occupational disease control to understand the harm of arsenic pollution. After discussing our project plan with Ms. Li.in detail, Ms. Li expressed high recognition for our project. Ms. Li explained that it is inevitable for people to daily intake a trace of Arsenic from surrounding environment. Thus, main precaution is to avoid contacting with the material containing Arsenic since Arsenic is unnecessary for human survival. Currently, some kinds of pollution, as such underground water pollution and soil pollution, are unavoidable.
Meanwhile, we gained further knowledge about the Arsenic’s damage to human body. Though as a kind of metal, Arsenic itself is low in toxicity, oxidized Arsenic has high toxicity, involving toxic chemical - Arsenic Trioxide (As2O3), also known as white arsenic. Arsenic poisoning mainly damages skin, nervous system, and liver. The skin damage could cause various clinical symptom: oxidized skin, hyperkeratosis (usually on palm sides and soles), pigmentation, and skin ulcer, which are the most obvious feature of Arsenic poisoning. In addition, as liver is the detoxifying organ of human body, all toxins will be filtered by liver, which results in many cases of liver poisoning. Furthermore, the most common symptom of nervous system is neurosis, known as neurasthenia, including dizziness, headache, and weakness.
We interviewed Ms. XiangYun Li in Wuhan occupational disease hospital.
After the expert visit, we determined the preliminary direction of our project, and tested the arsenic in different concentrations in the pollutants. Then, our group carried out brainstorming, literature investigation, and referred to previous iGEM projects. In the design of biosensor, we constructed our biosensor on the basis of BBa_J33201, which was registered by the Edinburg team in 2006. Using the principle of synthetic biology, we placed a strong RBS and report gene GFP protein downstream of the biosensor to construct our biosensor. If the project goes well, a convenient detection device can be made finally.
Interview with XiangRong Testing Company
After several months of testing and testing, the function of our test parts is still not ideal. For this reason, we interviewed the technican of Xiangrong testing company, hoping to get help. During the interview, we learned that the original physical and chemical detection methods have been very mature, such as atomic fluorescence spectrometer. Although biological method is very convenient to detect arsenic, it has little practical significance. After all, heavy metal pollution, such as arsenic, is also difficult to appear in daily life, mainly in industrial metallurgy. However, the current technical difficulty is to deal with it. This interview allowed our project center to shift to arsenic adsorption.
Interview with Professor JinJun Li in Wuhan University.
In order to confirm the direction of our project again, we interviewed Professor Li Jinjin from the school of resources and environment of Wuhan University, who is an expert focusing on heavy metal pollution control. We will tell him the progress of our project and the difficulties we are facing at present. He showed us the atomic fluorescence spectrum of arsenic detection. He told us that atomic fluorescence spectrum is an effective experimental instrument for arsenic detection, and provided us with an experimental platform and an experimental operation scheme to learn.
In addition, he provided us with two directions for reference on arsenic treatment. There are many ways of biosorption, he said. We can carry out projects in two directions: intracellular adsorption and extracellular adsorption.
1. Metallothionein (MT) plays an important role in the bioremediation of heavy metals. MT is a kind of small peptide with low molecular weight and rich Cys - residues, which can adsorb many heavy metals such as lead, mercury and cadmium.
2. For arsenic adsorption, Professor Li told us that there is another important protein with high affinity for arsenic adsorption called phytochelatin (PC). It was found that the arsenic adsorption capacity of PC was higher than that of Mt. We can consider refining our adsorption direction from this direction.
Survey results
Having understood Arsenic’s harm, we surveyed residents and students to ensure that if it is meaningful to detect and handle Arsenic. After collected both electronic and paper questionnaires, we analyzed the data inside and obtained the following results:
Introduction
Microbial remediation refers to a process of removing or rending harmless contaminations from soil and water by the action of microorganisms. The pollution of water and soil prevails around world especially the region or area which are developing and depends on mining, leading to serious consequences not only for people’s health but also for the farmland. To be more specific, for people, they will catch the disease like skin cancer and soon. For farmlands, it will make the soil be infertile so that difficult for plants and crops to grow, which bad for people as well. Thus, it becomes more and more necessary and important to control the contaminations of arsenic and take some measures as protection. Based on these facts, our goal is to develop a practical and useable machine, which can control the pollution of arsenic, remedy the contaminated soil, and filter the polluted water into fresh water, and try to promote it to the public. Through this questionnaire, it is our wish to know the different opinions about this idea and therefore help us acquire some advice and inspirations.
Sample description
A total of 433 samples in major provinces of China. The largest number of respondents was from Hubei. Sample age group, gender distribution is uniform, education background is mainly high school or above.
Knowledge about arsenic contamination
Question: What disease do you know that arsenic would cause?
Expectation and acceptance of Arsenic removal by bioremediation system
Question: Do you think it is necessary to make “Arsenic removal by bioremediation system” ?
Cognition of synthetic biology
Question: Do you agree to use synthetic biology to improve our environment?
Conclusion
The survey showed us the public’s concern about Arsenic pollution but little understanding about synthetic biology. However, we expected to, by using synthetic biology, fabricate a cheap, convenient biological device which can absorb Arsenic, and we proceeded the project in two ways.
Field Research in Yu Jia Tou Sewage Plant
During the field research, when we were talking about the Escherichia coli used in synthetic biology, the expert claimed due to the fact that E.coli is under the monitor of national environmental protection institutions, we should consider engineering bacteria’s influence on environment. But, he appreciated our idea of suicide gene and pointed out that the off-spring of E.coli should also be taken into consideration and if possible, sterilizing drugs containing chlorine and sodium chlorate can be put into the end part of our device.
