AI-2 production of S. oneidensis wild type, luxS mutant and WT control strain. All three strains were grown in LB at 30°C with shaking. Periodically, the growth was measured (OD600 nm) and sterile culture supernatants were collected and used to determine the produced AI-2. The AI-2 amount in the supernatant was detected by the V. harveyi bioassay and expressed in relative AI-2 amount. All strains grew at identical growth rates. The AI-2 production of the MR-1 wild type strain (WT) and the WT control strain (control strain) are indistinguishable, while that of the luxS mutant was at background level.