Team:UCAS
Degrading Antibiotic Residues in City Water Bodies
During the course of brainstorm, our team members came up with several ideas including treating diabetes using gut microbes, degrading PCBs in the environment and degrading antibiotic residues.After consulting professionals, we decided to work on degrading antibiotics for several reasons:
(1) Antibiotic resistant crisis has become a major threat to human health and it has attracted much attention worldwide in recent years. Since antibiotic contaminant is more eminent than others like PCBs, we decided to tackle this problem;
(2) China is by far the largest antibiotic producing and consuming country in the world, but it was not until recently that the public has been aware of the consequence of antibiotic abuse;
(3) Researches show that connection of antibiotic residues in city river is relatively high, so this is the practical use of our project;
(4) Thanks to the works finished by previous teams, we can utilize and enhance some of the submitted parts;
(5) While most of the previous teams focused on testing the antibiotics in natural environment or some products, we will focus on degrading the antibiotics. Evaluating the degrading efficacy of enzymes is a primary goal of our work;
Antibiotics have long been extensively used in agriculture, livestock husbandry and medical treatment, but the harm caused by the abuse of antibiotics has not been realized by human society until recently. Researches show that antibiotic residues in water seriously affect human health and ecological safety. China, as a country which uses excessive antibiotics, would suffer from the harm of drug residues more severely. In order to effectively degrade the antibiotic residues in water, the UCAS iGEM team 2016 hope to construct a kind of microorganism which is able to decompose antibiotics with high efficiency. We choose several oxidative methods to solve this problem, and screen several productive oxidases.
There are mainly three parts to our project.
(1)The selection of degrading enzymes: Before enzymatic reaction, we first used some active small molecules to test the degradation efficiency of antibiotics. However, the results are not promising, indicating that chemical compounds alone are not sufficient to degrade antibiotics. Next, we will try to practice enzymatic reactions to decompose antibiotics in vitro, and will compare the efficiencies with those of natural resistant genes, so that we would select one or a few oxidases. The enzymes we will screen includes a form of manganese peroxidase(MnCcp) and myoglobin mutants. We choose E. coli as the chassis organism, and evaluate the degrading efficiency in vivo.
(2)Genetically modified microbes(GMMs) threaten the environment once the artificial genes are transformed to other organisms or released. So we designed a kill-switch to prevent the horizontal-gene-transfer based on Type II TA modules commonly found in prokaryotes. In this summer, we will measure the toxicity of different types of TA modules, in order to screen out the most toxic ones. In addition to test the activity of different toxins independently, we will also come up with a method to label and quantify the amount of toxins expressed in cells, and to compare the toxicity per unit between varies kinds of toxins.
(3)Circuit design: We hope that the expression of antibiotic degrading enzyme and the TA module could be tightly regulated by signals outside. So in this part, we will utilize the tetracycline sensor constructed by BIT and make improvements to it by adding a positive feedback. We are also expected to further characterize this circuit. We will also test the TA module regulation circuit reported in some research papers.
