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From 2012.igem.org

Our construct idea is simple: production of pigment under the regulation of rotten-meat reactive promoter. When the Bacillus subtilis senses the volatiles from the rotten meat, the rotten meat promoter becomes active thus allowing the production of downstream genes. We put pigment genes available downstream of the promoter so that the pigment would be produced when the promoter is activated.

We use our Bacillus subtilis backbone (BBa_K818000) that has sacA and chloramphenicol resistance gene for chromosomal integration and transformants antibiotic screening. This backbone also has E. coli origin of replication, so it can be amplified inside E. coli.

There are several ideas to improve our current construct, such as: multi-colored pigment system and fine tuning of the pigment production.


Multi-colored Pigment System

This idea basically mimics the traffic light function: different colors production for every state of the meat. When the meat is still fresh, a specific pigment will be produced. When the meat starts to rot, another pigment will be produced overriding the previous pigment. This can be accomplished by either producing different pigments at different stage of the meat or by producing a specific pigment at fresh meat stage and then produce a compound that reacts to the produced pigment causing it to change color.


Fine Tuning of Pigment Production