Psidium guajava
Erwinia psidii is a Gram-negative 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 signaling substances, and employed in bacterial cell-to-cell communication systems.