Quorum sensing is an organic chemical signal that regulates a variety of physiological activities of bacteria, such as cell movement, growth, and biofilm formation. This sensing mechanism is mediated by diffusible chemical signals called homoserine lactones. The concentration of signal molecules outside the cell increases with increasing cell density and the signal molecule itself is permeable to the cell membrane. Upon reaching the threshold concentration of the chemical signal, the quorum sensing system is activated to trigger expression or inhibition of the gene.
We used the quorum sensing system of iron bacteria isolated from pipeline rust. This system is homologous to the LuxR system. The iron bacteria itself produces the AfeR protein, which binds to 3-oxo-C12-AHL and dimerizes. This dimer binds to afeR box and activates gene transcription. Therefore, the recognition of iron bacteria by Escherichia coli can be achieved by constructing a heterologous AfeR protein of iron bacteria and a corresponding activated promoter in engineered E. coli.
Gene fragment of GFP is synthesized through Genescript and it is on vector pUC57.
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