[Growth and mutation of Escherichia coli with suicide gene circuit based on quorum sensing]

Constructing robust gene circuits is a fundamental work for synthetic biology. Bacteria with suicide gene circuit based on quorum-sensing will kill themselves in a controllable pattern upon certain cell density. In the media of different IPTG inducer concentration, we observed the growth and suicidal behavior of the Escherichia coli. Top10F' with such gene circuit, screened the mutants and determined their mutated loci. The results show that, with higher IPTG concentration, the more wild type bacteria were killed; as well the mutants emerged earlier and spread over the population more quickly. The sequence of plasmids in those mutants revealed that a transposon inserted into the luxR gene and therefore disrupted Quorum-Sensing of these individuals. Furthermore, the insertion sequence of the plasmid can solely result in the mutants escaping from suicide.