Team:Sorbonne U Paris/Description
Description
"The Chlamy Cleaner" project
Our 2020 iGEM team is composed of students from Sorbonne Université (Paris, FRANCE), initially drawn from diverse backgrounds but sharing a common passion for science and innovation. Our project entitled “The Chlamy Cleaner”, consists of making the photosynthetic green microalgae named Chlamydomonas reinhardtii efficient for bioremediation of hazardous compounds found in the water of the Seine river which are not treated by wastewater treatment plants. We want to improve the abilities of Chlamydomonas to actively bioremediate micropollutants. We focus on a very persistent pesticide called Atrazine that was massively used in the agronomic field.
Our strategy
Given that atrazine can be degraded by microbial communities in water and soil environments, we decided to enhance the biodegradation abilities of the microalgae
Chlamydomonas reinhardtii
to make it a suitable tool for water bioremediation. To achieve this goal, our project is divided into two parts. First, we implemented an atrazine degradation pathway coming from
Pseudomonas sp. ADP
strain, containing the
atzA,
atzB
and
atzC
genes. These enzymes metabolize atrazine into cyanuric acid, a less toxic compound.
In the second part of our project, we imagined a kill switch device to prevent any environmental pollution due to an accidental spread of our engineered Chlamydomonas reinhardtii strain. Based on a UV-light sensitive programmed cell death, this safeguard relies on the release of a
nuclease
anchored on the plasma membrane induced by
COP1
and
URV8
dimerisation. The Golden gate Molecular Cloning (MoClo) technology, based on type II restriction enzymes, was used to assemble these two functions into
Chlamydomonas reinhardtii
.
Wastewater treatment plant
We highlighted that the Seine is polluted with plenty of different contaminants. In addition to the plastic and the different objects thrown in the Seine, the antibiotics rejected in wastewater from hospitals, the hormones rejected by women taking the contraceptive pill and the pesticides from agriculture’s wastewater are also a real hazard. Very specific filters are required to get rid of these small molecules. The current wastewater treatment plants, which are determinant to purify the water, do not have this kind of specific filters. Indeed, in wastewater treatment plants, the water goes through grids and sieves to rid it of the objects and the big particles. The next step consists of eliminating the suspended solids remaining and the phosphorus. Finally, another process leads to the removal of carbon and nitrogen, after which the water is released. Our main issue is the resistance of antibiotics, synthetic hormones and pesticides to these treatment methods.
Persistence of these micropollutants and their negative impact on the environment and public health show that improving water purification techniques is essential. Our team worked specifically on one of them, atrazine, but other pollutants are also very toxic.
