For our third participation in the iGEM competition, we decided to use a new chassis which is able to work in the depth of oceans through a forceful duo: sponge and bacterium. Sponge can filtrate up to 20m³ of water/day/kg thus being one of the most powerful existing filtrating system. We focused on the sponge Spongia Officinalis, which lives in episymbiosis with the bacterium: Pseudovibrio denitrificans.
Pseudovibrio denitrificans is a marine bacterium which as been not yet characterized and also never been used in iGEM.
Likewise, we bring in the iGEM competition Spongia Officinalis, a sponge with impressive features and capacities.
This is why we dedicate a part to introducing them.

Our synthetic system is based on the bacterium Pseudovibrio denitrificans, which is yet arduous to transform due to its marin origin. In order to be able to transform our bacterium with genes of interest, we have created a new backbone enabling us to use the transposon system in our bacterium. This tool allows to insert genes easily into unknown bacteria.

This year, our team objective is to develop a filtrating system allowing the sensing and eventually degradation of pollutants. To achieve that goal, we have chosen to work on the most important classes of marine pollutants: phenols, PCBs, nitrites and heavy metals.

This year, we decided to include in our project a philosophical reflexion on the methods used in iGEM and in synthetic biology. We observed that there was an important contrast between what synthetic biologists ambition to do — a rational, rigorous design with controlled and predicted results — and how they actually design their biological systems — by trial and error, and tinkering. As students engaged in the practice of synthetic biology, we thought that it was very important to take a critical look at the field, and to question whether design in synthetic biology can truly be compared to engineering, or if it is instead the result of inelegant but efficient kludges. Since our project means to use sponges as part of our biosensing agent, we also discussed the ethical issues raised by the modification of an animal's microbiome, and by the use of an animal as a bioremediation tool in potentially toxic areas. We also had an important reflexion about the risks inherent to the release of genetically modified organisms in seawater, and tried to assert whether a symbiosis between the bacteria and the sponge could be a safe and efficient biological containment of the engineered micro-organisms.

This year we provided two models of the sponge, and also two sensors models. Concernerning the sponge sponge modethe first model was a flux model of the sponges in one dimension. The second model is a 2D diffusion model. It t ake into accoun the number and the size of the sponge spore. We also model two sensor model. The first one about the PCB and the second one for the phenol. The phonol model acess the biological results