Welcome to the Paris-Saclay iGEM 2013 Wiki

Our project

PCBs (Polychlorobiphenyls) are synthetic chemicals that were largely used in electrical equipment during the second half of the 20th century. These hazardous organic compounds are very stable and not readily biodegradable. Thus, they remain for many years in nature and belong to family of persistent pollutants. Because of their lipophilicity, PCBs accumulate in animal fatty tissues, starting from aquatic organisms and going up the food chain. Indeed, they can be found in high concentrations in human adipose tissues. As most PCBs are probably carcinogenic (class 2A) and some are recognized endocrine disruptors, they represent an important health issue. This is especially true in France where a study showed higher levels of PCB in French people adipose tissues than in other populations.

Although PCBs are man-made and have no natural equivalents, some bacterial communities have evolved and developed the capacity to degrade PCBs. Degradation of highly chlorinated PCBs begins with an anaerobic reductive dechlorination that lowers the number of chlorine atoms bear by the PCB molecules. PCBs with few chlorine atoms can then be degraded by using the biphenyl degradation pathway.

Our project aims at constructing an Escherichia coli strain capable of degrading highly chlorinated PCBs. This will be achieved by introducing in an E. coli strains genes involved in the degradation of PCBs from the three most efficient PCB degrading strains described so far: Pseudomonas pseudoalcaligenes, Burkholderia Xenovorans and Rhodoccocus jostii. Because the first degradation steps are anaerobic and later steps are aerobic, we want to introduce an oxygen based regulation of the expression of the different genes implicated in both aerobic and anaerobic degradation steps. Finally, we are also developing a sensor system to detect PCBs in the environment.