Quorum sensing is a regulatory system used by bacteria for controlling gene expression in response to increasing cell density. Controlling bacterial infections by quenching their quorum sensing systems is involved in a promising field of study. The expression of specific target genes, such as transcriptional regulators belonging to the LuxIR family of proteins, is coordinated by synthesis of diffusible acylhomoserine lactone (AHL) molecules. N-heptanoyl-L-Homoserine lactone (C7-HSL) is a small diffusible signaling molecule involved in quorum sensing, thereby controlling gene expression and affecting cellular metabolism. [1] [2] The diverse applications of this molecule include regulation of virulence, infection prevention, and septicemia in fish. [3]

Reference:
[1]. Lithgow, J.K., Wilkinson, A., Hardman, A., et al. The regulatory locus cinRI in Rhizobium leguminosarum controls a network of quorum-sensing loci. Molecular Microbiology 37(1), 81-97 (2000).
[2]. Barnard, A.M.L., and Salmond, G.P.C. Quorum sensing: The complexities of chemical communication between bacteria. Complexus 5(2), 87-101 (2004).
[3]. Morohoshi, T., Inaba, T., Kato, N., et al. Identification of quorum-sensing signal molecules and the LuxRI homologs in fish pathogen edwardsiella tarda. Journal of Bioscience and Bioengineering 98(4), 274-281 (2004).