• Home
• Foundational Advances
• MiniTn7
• Overview

MiniTn7

Development of BioBrick parts relies heavily on the use of a set of plasmid vectors that are only replicative in Escherichia coli and the enterics. While this approach has been successful for many projects, there are a number of concerns that we believe should be addressed in order to augment the palette of possibilities that can be exploited in Synthetic biology based on standard parts.

• Plasmid stability. Although many plasmids are relatively stable in a culture setting, it is customary to maintain antibiotic selection to prevent plasmid loss, but this is often not possible in an industrial setting or in the environment. A small subpopulation lacking the plasmid may quickly overtake the culture, especially after repeated subculturing, because of the relief of the energetic burden of plasmid replication.

• Plasmid copy number. Plasmids are extrachromosomal genetic elements that occur in a variable number of copies. Plasmids generally used in iGEM range from 15-20 to nearly 2000 copies per chromosome. In addition, the plasmid copy number may fluctuate from cell to cell due to drift in the replication process. On the other hand, many Synthetic biology projects require rewiring regulatory circuits with components that are not meant to be present in multiple copies. This may provoke unwanted effects, such as the titration of trans-acting elements, that lead to a decrease in the robustness of the resulting circuit.

• E. coli as a host. E. coli is the workhorse of genetic engineering. Because of its easy and fast growth in culture and the extensive knowledge accumulated on its genetics, metabolism and physiology, it is appropriate for many applications. However, there are others for which it is a better choice to use a different microbial host. For example, E. coli does not survive well in the environment, particularly in soils, and it is therefore unsuitable for many environmental applications.