Peptide-based quorum sensing systems in .

is an agriculturally important plant growth-promoting rhizobacterium. Many species are known to be engaged in complex bacteria-bacteria and bacteria-host interactions, which in other species were shown to necessitate quorum sensing communication. However, to date, no quorum sensing systems have been described in Here, we show that the type strain ATCC 842 encodes at least 16 peptide-based communication systems. Each of these systems is comprised of a pro-peptide that is secreted to the growth medium and processed to generate a mature short peptide. Each peptide has a cognate intracellular receptor of the RRNPP family, and we show that external addition of communication peptides leads to reprogramming of the transcriptional response. We found that these quorum sensing systems are conserved across hundreds of species belonging to the family, with some species encoding more than 25 different peptide-receptor pairs, representing a record number of quorum sensing systems encoded in a single genome.