BioBuilder

Chapter 6. Eau That Smell

The Eau That Smell lab emphasizes the “test” phase of the engineering design-build-test cycle. You will test two different synthetic living systems, already designed and built by other engineers. There are two design options for you to compare. Both of these designs change the smell of normally stinky bacteria, and both look like they could be “right.” In comparing the designs, there will be opportunities to explore how synthetic biologists make design choices as well as to learn and teach some important scientific ideas about gene regulation and cell growth. This activity was inspired by an International Genetically Engineered Machines (iGEM) project from 2006 in which a team of undergraduates from MIT designed a new strain of bacteria they called “Eau d’coli.” The team generated a strain of E. coli that smells like bananas or wintergreen, depending on the growth phase of the cells. The BioBuilder laboratory activity looks at two genetic programs that control the relationship between cell-growth cycle and scent generation. On paper, the two design options appear nearly equivalent, but real-world behavior often deviates from expectations, so the laboratory activity allows for direct testing of the strains described here. Before detailing the experiment, we will walk through the iGEM project on which it’s based to offer context, and also to provide an ...