Every year, one third of global food production -1.3 billion tons of food- is thrown away, partially due to the “best before” dating system. iGEM Groningen 2012 seeks to provide an alternative method of assessing edibility: the Food Warden. It uses an engineered strain of Bacillus subtilis to detect and report volatiles in spoiling meat. The introduced genetic construct uses a promoter to trigger a pigment coding gene. This promoter, identified by microarray analysis, is significantly upregulated in the presence of volatiles from spoiling meat. The activity of the promoter regulates the expression of the pigment reporter and will be visible to the naked eye. For safe usage of the system, spores of our engineered strain are placed into one half of a semi-permeable capsule, the second containing a calibrated amount of nutrients. Breaking the barrier between the two compartments allows germination and growth, thereby activating the spoiling-meat sensor.

Completed after European Regionals

Tested a construct with downregulated promoter WapA
Performed enhanced construct characterization
Characterized the influence of oxygen on germination and growth within the sticker
Expanded the scope of the market survey
Collaborated with Cambridge 2012

Our main accomplishments

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We designed and tested the "Sticker": a capsule in which bacteria are kept inside and volatiles can go through. We used a model to get insight on how to tweak the growth of Bacillus subtilis.

2. We explored the definition of spoiled meat and ways to check meat spoilage. We identified various compounds present in spoiled meat.

3. We identified spoiled meat sensors by transcriptome analysis.

4. Backbone pSac-Cm: easy cloning in
B. subtilis, the BioBrick way, for the first time! It's easy to check, BioBrick compatible, E. coli compatible, stabily inserted into the B. subtilis chromosome.

We made AmilCP and AmilGFP suitable for expression in Bacillus subtilis.
These chromoproteins can be of significant value to the other Bacillus subtilis users in the BioBrick community.

6. Most importantly: we developed a construct which makes Bacillus subtilis sense spoiled meat and produce an output in the form of a yellow or purple pigment visible by naked eye.

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