Team:Lyon-INSA-ENS/Project/ContextFr
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- | + | En subissant un bombardement neutronique en provenancce du réacteur, les métaux stables se transforment en 60Co | |
- | ( | + | (demi-vie = 5,3 ans) et 58Co (demi-vie = 71 jours). La capture du cobalt est intéressant du point de vue <b> sanitaires </ b> puisqu'il représente un danger <b> sous ses deux formes radioactives et stables (cancérigènes) </ b>. Cela représente également un avantage sur le plan <b>environnemental</ b> en évitant la contamination des eaux, des sols et des eaux souterraines. Même avec une courte demi-vie, le cobalt 60 émet des rayons gamma de haute <b> intensité </ b>, et se désintègre en nickel, élément stable, mais polluant. |
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Revision as of 16:04, 20 September 2011
Le projet "Cobalt Buster"
- Surproduction de Curli via un opéron synthétique contrôlé par le promoter Prcn-csgBAEFG inductible par le cobalt
- Surexpression du gène Curli via le superactivateur OmpR234
- Ingénerie chez E. coli au niveau de l'adhésion afin d'améliorer la bioremédiation
Surproduction de curli via un opéron synthétique contrôlé par le promoter Prcn-csgBAEFG inductible par le cobalt
![](https://static.igem.org/mediawiki/2011/e/eb/Schema_projet.png)
Surexpression du gène Curli via le superactivateur OmpR234
![](https://static.igem.org/mediawiki/2011/1/19/Schema2.jpg)
Ingénerie chez E. coli au niveau de l'adhésion afin d'améliorer la bioremédiation
Biofilms et dépollution. Souvent associé à des maladies et un encrassement non voulu des surfaces, les biofilms ont un un intérêt dans la bioremédiation, la biocatalyse ou comme biocarburant. Les procédés de bioremédiation utilise la capacité microbienne naturelle à dégrader les substances organiques ou à modifier la spéciation des métaux en les immobilisant ou en les rendant volatils. De telles propriétés sont observées dans les écosystèmes naturel ainsi que dans des systèmes artificiels utilisées pour nettoyer les déchets solides ou liquides. L'intensité et la qualité de cette activité microbienne dépend de facteurs physiques et chimiques locaux,mais aussi de la voie choisie par les bactéries (biofilm ou planton). La formation de bofilm est associée à la résistance à la plupart des biocides par divers mécanismes. L'adhésion est donc une propriété de choix dans la plupart des processus remédiation.
Strategy: boost natural abilities! Binding to extracellular matrix, efflux pumps and activation of transporters allow concentration and sequestration of biocides such as metals. Genetic engineering allows to boost these activities and to improve the treatment of metallic pollution, especially for toxic metals in low concentration. Classic chemical processes using ion-exchange resins are then economically inappropriate, and thanks to their high selectivity, micro-organisms appear very efficient.
OGM biofilters for nuclear liquid waste treatment. Treatment of nuclear waste is a promising application for biological treatment of metals contaminations. Confinement is indeed a major hindrance to the use of Genetically Modified Organisms for waste treatment. Since radioactive waste are submitted to a strict and regulated handling, use of GMO in this context should be well-accepted by the society. The activity of modern nuclear power plants with pressurized water reactors generates radioactive effluents that contain among others radioactive cobalt. The tubing of the cooling circuit is made of a steel alloy rich in cobalt and nickel. Under neutrons bombardment coming from the reactor, these stable metals change into radioactive isotopes.
![](https://static.igem.org/mediawiki/2011/4/4f/Interrogation.jpg)
Corrosion results in solubilization of these activation products, and water contamination.
Selective cobalt capture. Controlled immobilization of radioactive cobalt is both an important sanitary and environmental issue. Activation products are routinely captured by using synthetic ion exchangers. This generates large volume of solid waste due to the nonspecific nature of ion sorption. In this context, a researcher from the Lyon INSA-ENS team has recently constructed an E.coli strain able to eliminate 85% of radioactive cobalt initially present as traces in a simulated nuclear effluent.
![](https://static.igem.org/mediawiki/2011/4/4f/Interrogation.jpg)
* rcnA = resistance to cobalt and nickel
However, the recovery of cobalt-fixing bacteria has to be facilitated before to consider industrial application.
“Cobalt Buster” biofilter. Our objective is to facilitate the recovery of the metal-stuffed bacteria by inducing their fixation to a solid support. (France 3 movie?). We choose to engineer this sought-after adherence property by using the exceptional properties of the curli amyloid fibers. In a first approach, a synthetic operon comprising the absolutely required genes for curli production under control of a strong and cobalt-inducible promoter was designed and synthesized. This construct allows K12 E. coli (MC4100, MG1655, NM522…) to stick to polystyrene and glass. Adherence is reinforced by the presence of cobalt and should avoid free floating growth. In a second approach, a part allowing the constitutive overproduction of the curli superactivator OmpR234 was constructed. By activating the cryptic curli genes located in the core genome of K12 E. coli, this part allows to increase bacterial adherence to polystyrene and glass. Such results lead us to discuss of a possible industrialization with the ASSYSTEM company and of research and development perspectives with the EDF company.