Comment in Nature Biotechnology 31, 952–954 (2013); doi:10.1038/nbt1113-952b Published online: 08 November 2013
At the beginning of this month, the International Genetically Engineered Machine competition (iGEM) 2013 convened at the Massachusetts Institute of Technology in Cambridge, Mass. Last year's winners designed a device that can detect spoiled meat (2012.igem.org/Team:Groningen). Team Groningen 2012 developed a biosensor that can judge whether meat is still fresh based on its odor. The researchers used a Gram-positive model bacterium generally regarded as safe, Bacillus subtilis, as a 'chassis' for their invention called the Food Warden. With standardized synthetic biology building blocks—BioBricks—they assembled a construct which encodes a chromogenic readout whose expression is controlled by a promoter that is activated in response to volatiles released by rotting meat. When expressed in the bacteria, in the presence of volatiles from spoiled meat, the reporter-strain produces yellow or violet pigments that are visible to the naked human eye. The team proposes that spores of the biosensor–containing B. subtilis, or engineered psychrotrophic Bacillus, be added to meat packaging systems.