Erwinia psidii is a Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 bacterium and a phytopathogen of the Common Guava (Psidium guajava), causing rot in branches, flowers and fruits. Recently, it was demonstrated that this species produces two acyl-homoserine lactones (S-(-)-N-hexanoyl- and N-heptanoyl-homoserine lactone), widely recognized bacterial quorum sensing

Quorum sensing

Quorum sensing is a system of stimulus and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In similar fashion, some social insects use quorum sensing to determine where to nest...

signaling substances, and employed in bacterial cell-to-cell communication systems.