Second, thanks to our knowledge accumulated on photosynthetic bacteria, we have been coordinating a collaborative project funded by the Life+ program (an EU's financial instrument) to demonstrate an innovative process for treating phytopharmaceutical effluents (pesticides) with the development of demonstrators on site. The treatment is based on the use of photosynthetic microorganisms shown in the lab to be efficient to degrade active molecules, including organophosphates. The process consists in a series of three lagooning basins supplied via a washing station (for farm machineries) that recovers phytopharmaceutical residues. The basins are unventilated and cascading, and are seeded with a bacterial consortium selected by the laboratory to degrade active molecules in the effluents. Monitoring of the pesticides charge conducted in different farms indicates an almost complete degradation of most of the active molecules discharged into the ponds. Conservation in the most suitable packaging for a simple and easy manipulation by non-specialist users is also addressed and the creation of a startup company to exploit this process is currently under consideration.​

For more updated information on this project, connect to the following link: http://www.lifephytobarre.eu/​

Green Chemistry

We also investigate the magnetization properties of Magnetotactic bacteria for the construction of recyclable biocatalysts. Magnetosomes functionalization can thus be achieved by translational fusion coupling a membrane anchor to an enzyme of interest (7). As a result, biocatalysts are synthesized and immobilized on the magnetic nanoparticles by the cellular machinery, and they can be simply recovered  after purification of the magnetosome using magnetization,. The applications of such a process are numerous both in environmental and health biotechnologies.

Biotechnology for health

Magnetosomes are unique biogenic nanoparticles with a large potential in health biotechnology. Isolated magnetosome crystals are indeed superior to synthetic particles because of their unique characteristics: (i) a perfectly crystalline nanocrystal of magnetite, with contrasting properties for magnetic resonance imaging (MRI); (ii) magnetic properties that allow easy separation or guidance; (iii) a natural lipid bilayer coating the nanoparticles, ensuring their solubilization; (iv) a possible functionalization of the lipid surface with biological functions for cellular targeting or in situ enzymatic catalysis. In the last period, we coordinated a collaborative project (MEFISTO, ANR P2N) that focused on the use of magnetosomes in the localized treatment by hyperthermia of cerebral tumors assisted by high-field MRI diagnostics (in collaboration with Neurospin, CEA Saclay). While MTB are difficult to grow in large quantities, we first succeeded in setting up the semi-automated, large scale production in 7 liters bioreactors of two magnetotactic strains, Magnetospirillum magneticum AMB-1 and Magnetovibrio blakemorei MV-1. We also devised new extraction, purification and characterization protocols to obtain large quantities of magnetosomes required for further biotechnological developments. We demonstrated that the systemic injection of purified wild-type magnetosomes reveal the mouse brain vasculature (ACL7.53). Based on previous magnetosomes functionalization experiments for bioremediation (ACL7.5), we genetically functionalized the outer surface of the magnetosomes membrane with a RGD peptide known to specifically target a_nb₃ integrin receptors generally expressed at the surface of cancer cells during angiogenesis. The ability of purified RGD-magnetosomes to target these receptors was evidenced in vitro on U87 cells (human glioblastoma) overexpressing the a_nb₃ integrin receptors by immuno-, histo- chemical staining and fluorescence microscopy while in vivo MRI at 11.2 T revealed the enhanced retention time of the RGD-magnetosomes within the tumor compared to the wild-type magnetosomes (publication under submission). These results pave the way to future treatment of glioblastoma-bearing mice with magnetic hyperthermia after RGD-magnetosomes systemic injection and under MRI diagnostics. ​