Difference between revisions of "Part:BBa K540000"

Revision as of 22:49, 20 September 2011

rcn-csgBAEFG, over-induces adherence in response to cobalt

This parts associates the rcn promoter, whose expression increases with cobalt in the medium, with csgBAEFG, an operon that enables the production and secretion of curlis, which are adherent proteins. It contains the necessary RBS to work. With this part, strains can become adherent in response to cobalt in the medium. This part may also make bacteria adherent in response to nickel, which has however not been studied.

Characterization

MC4100 bacteria have been transformed with this part. The transformed strain is called S26, while the negative control is called S25.

In the following experiment, we are testing both the effect of this part on the bacteria, and the response to cobalt with and without the added part.

24-well plates have been seeded by both strain, with increasing cobalt concentration. This experiment has been repeated several times, by different students. Total OD measurement shows the relative growth of the bacteria in the different well, while the OD measurement of the fixed fraction of bacteria will reveal the effect of the part on biofilm formation.

The graph shown above demonstrates that total OD does not vary significantly with different medium conditions.

This implies that adding the part, or cobalt in the medium does not impact the growth of the tested bacteria, and that differences in OD between wells will be significant.

From the graph above, we can draw 2 conclusions :

• A significant increase in adherence is observed by Co concentration ranging from 0 to 25 µM
• For higher concentrations, the adherence seems to be stable, or only slightly increasing.

Conclusion: this part creates in new effect in transformed bacteria : cobalt makes them produce curli, in turn increasing their overall adherence.

Safety

This part is not toxic by itself. However, when using this part, you will probably need to handle cobalt. Cobalt is toxic in all its forms ( ionic or metallic ) by inhalation, ingestion or contact. Wear adapted personal protection equipment ( labcoat, safety glasses, safety gloves ) and dispose of it in appropriate waste containers.

Usage and Biology

This part was designed to be used in a strain with enhanced cobalt capture capacities ( like the one described in [1]). That way, the strain captures cobalt in the medium and becomes adherent, which allows it to be easily separated from the medium. Possible applications include bioremediation of radioactive cobalt in nuclear power plants, using this adherence property to build a biofilter.

[1] Bioremediation of trace cobalt from simulated spent decontamination solutions of nuclear power reactors using E. coli expressing NiCoT genes. Raghu G, Balaji V, Venkateswaran G, Rodrigue A, Maruthi Mohan P. Appl Microbiol Biotechnol. 2008 Dec.

Sequence and Features