 First identified in the marine bacterium "Vibrio harveyi", AI-2 is produced and recognized by many Gram-negative and Gram-positive bacteria.AI-2 arises by the reaction of 1-deoxy-3-dehydro-D-ribulose, which is produced enzymatically with boric acid, and is recognized by the two-component sensor kinase LuxPQ in Vibrionaceae.AI-2 is actively transported by the Lsr ABC-type transporter into the cell in Enterobacteriaceae and few other bacterial taxa ("Pasteurella", "Photorhabdus", "Haemophilus", "Bacillus"), where it is phosphorylated by LsrK.