autoinducer

noun

au·to·in·duc·er ˌȯ-tō-ˌin-ˈd(y)ü-sər

plural autoinducers

microbiology

: a molecule produced and secreted by bacteria that when present at a threshold concentration in a population of bacteria signals genetic expression in the same bacteria from which it was produced

When a crowd of bacteria and their autoinducers become dense enough, the lights in all the bacteria switch on at once.—

Wendy Orent, Discover, July/August 2009

The synchronous response of bacterial populations to autoinducers confers a form of multicellularity to bacteria.—

Andrew Camilli and Bonnie L. Bassler, Science, 24 Feb. 2006

Note: Autoinducers are involved in the quorum sensing used by some bacteria to detect their population density and coordinate group actions (such as the formation of biofilms).