We have turned engineering a gene into engineering a pathway, and we have made lots of approaches to maintain stability of the whole system. In terms of cells, it is difficult to satisfy what we need if only by engineering a cell, because we require a mixture of different kinds of cells to do more complex tasks. However, it is still very difficult for us to build such a mixed system, and the priority is how to balance a suitable rate of different cell quorum. An appropriate proportion is important to the correct results and max efficiency.
![](https://static.igem.org/mediawiki/2012/c/cf/SYSU-overview.jpg)
To accomplish this function, we found several proteins which can inhibit E.coli replication initiation, and we also built a “quorum density inducible— bistable switch” to gain a new balance.
This system is not only useful for acquiring suitable proportion of a mixed culture quorum, but also has a great theoretical significance and application value as we proved below.