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Team:Peking
From 2014.igem.org
Harmful algal bloom
Widespread water bloom leads to extensive damage in ecosystems. Compared to physical or chemical methods, biological treatment for water bloom is less expensive and more environmentally friendly. Hence Peking iGEM is dedicated to constructing engineered microorganisms for the elimination of algae and recovery of ecosystems. A specific antimicrobial peptide is secreted to disrupt the outer membrane of algae. In addition, we equip our transgenic cells with features that allow for buoyancy and attachment, making our project more efficient. During this process, an enzyme is also secreted to degrade a deleterious product of algae. After eradicating the algae, our engineered bacteria will commit suicide, and the ecosystem is finally restored. This project is an innovative treatment for water bloom, and has potential applications in the field of ecosystem remediation.
Killing:
To achieve the goal of killing we make use of hen egg lysozyme, which can cause the cleaving of the glycosidic in the cyanobacteria`s peptidoglycan, thus cause the lysis of cyanobacteria. Our hen egg lysozyme can be secreted successfully with the help of ABC transporter. Besides, our E.coli can express yfkE, a kind of lysozyme inhibitor, to protect it from lysis.
Killing Improvements:
We expressed a lectin of the cyanobacetria on the surface of our E. coli cells so that they can bind to the cyanobacteria. According to computational models, binding of E. coli to the cyanobacteria greatly enhances the killing efficiency of our project. We also equipped our E. coli with gas vesicles so that our project can be feasible in the real ecosystems.
This year Peking iGEM aims at dealing with the problem of water bloom with the tool of Synthetic Biology, to engineer bacterial that can restore the ecosystem, both reduce the algal biomass and degrade the toxin.
Degradation :
Microcystis aeruginosa is the most common cyanobacteria during algal bloom, and can secrete microcystin, a deadly toxin. To decrease the negative effects of the toxin on water ecosystems, we introduce an engineered bacteria that can secrete a microcystinase-mlrA protein to hydrolyze the toxin.
Suicide :
In order to successfully solve the algal bloom, our team must put our engineered bacteria into the real ecosystems. If bacteria put into the real ecosystems are out of control, they may cause a lot of harm to local environment. So we must limit their life span and space they live in to a certain degree. One possible approach is that we artificially control their death. Therefore, we construct the suicide part to control the engineered bacteria using phage lysis system.
Modeling :
Our modelling focuses on supporting the whole project: doing numerical analysis and improving the applicability of ours design. We analysis Killing effect combined with Binding by using Monte Carlo simulation to optimize the project efficiency while minimize the cellular burden. We also develop phenomenological sound model for interpretation of gene expression by coupling cell physiological state, gene specific regulators and growth rate.
Human Practice :
Algal blooms threaten the ecological integrity and sustainability of aquatic ecosystems, they can not only deplete oxygen upon bloom senescence thus being harmful to the phytoplankton, but also produce a variety of toxic secondary metabolites.
There are some methods to deal with water bloom, such as physical methods, chemical methods, and biological methods. They each offer their own advantages, but also have their own disadvantages as the following table shows.
