Our lab

We carried out our experiments in the LISM (Laboratoire d'Ingenierie des Systèmes Macromoléculaires : Macromolecular Systems Engineering Laboratory) which since 1992 has been an internationally renowned laboratory doing fundamental research at the frontiers between Microbiology, Biochemistry, and Cell Biology. Located in Marseille it groups 50 scientists passionate about the molecular mechanisms of biology. One of their analysis rooms (Figure 1) was reserved for us for 3 months from June to August.

Organisms and enzymes used

Our main goal is to reduce microplastic pollution in the sea. In this matter, we plan to engineer a "plasticosome" capable to do so. Indeed, Escherichia coli will be engineered in order to be able to produce and secrete this structure capable of degrading microplastic and more specifically the 3 categories of plastic most present in de Mediterranean Sea (polyethylene, polypropylene and polystyrene), which is one of the most polluted seas in the world. This plasticosome is in fact a modified cellulosome (from R. cellulolyticum) which its CBM (Carbohydrate binding module) in PBM (Plastic binding module) thanks to nanobodies with high affinity for these types of plastics. In fact, this nanobodies will be selected by the phage display technique (M13K07 Helper phage, M13 phage).

This plasticosome which will have a high affinity for PE, PP and PS microplastic, will have as well at its surface different types of enzymes capable of degrading this type of plastic. These enzymes will be fused with dockerins, a protein which interact with cohesines the structure proteins from the cellulosome.
We will start with one type of enzyme, the laccases. These enzymes are more and more studied for their degradating activity of very big polymers such as plastics. The laccases that we will use are the Laccase from B.subtilis and T.versicolor because in recent scientific papers they have been characterized for having a greater activity against polyethylene, polypropylene and polystyrene.

Hazards

We received a safety and security formation (lab rules, biosafety equipment, biosecurity, waste management system, special protocols) as we arrived in the lab. We did have a Biosafety cabinet class II in order to work with our bacteria to limit the risk of contamination. Toxic chemicals were kept in special rooms, and we wore gloves and blouses when handling them under the fume cupboard (required). We used to disinfect our bench every time we used them. Contaminated waste with bacteria were going in a decontamination tank or directly in a special bin.