Overview!

The purple non-sulfur photosynthetic bacteria (PNSB) belong to the alpha-proteobacteria group, because of their genetic regulatory systems which coordinate different metabolic states, these microorganisms are able to grow under a wide variety of environmental conditions (1).
Specifically, our project aims to isolate two genetic control systems based on R. sphaeroides photosynthesis cluster regulation. The first one is the oxygen dependant system PrrA/PrrB, when oxygen tension is high it remains inactive, and when the oxygen is low it activates gene expression (2). The second system is the light and oxygen mediated system AppA/PpsR that represses gene expression under aerobic conditions and allows transcription in the absence of oxygen and light (3).
To achieve this goal we designed a genetic biobrick in which GFP expression is oxygen and light-dependent by the antirepression of PpsR and oxygen dependent by the activation of PrrA/B system. The lab work is accompanied by a computational model, which will provide a way of testing our knowledge of these systems.
Once, we have characterized the functionality of these regulatory systems we aim to take advantage of R. palustris’ metabolic versatility, and use this bacteria as a microbial factory, that could work for the production of metabolites with economic value products using CO2 as carbon source.
We are planning to use the S04147 clostridial butanol production operon (University of Alberta iGEM Team 2007) to evaluate the synthesis of this biofuel, linking it to our control systems. This would provide an interesting way to produce butanol using CO2 as carbon source under anaerobic photosynthetic conditions.