Fig 5.

AI-2 production profile of the Y. pestis Δlsr mutant and quantification of signal levels. (A) Yersinia pestis strain R88 and the Δlsr mutant were grown with shaking in BHI broth at 30°C. At each time point during growth, cell supernatants were collected, filtered, and assayed for AI-2 by using the V. harveyi MM32 reporter strain. (B) AI-2 was biosynthesized by using purified Y. pestis CO92 Pfs and LuxS enzymes (see Materials and Methods). A standard curve was prepared by using synthesized AI-2 in the V. harveyi bioassay. (C) Conversion of the bioluminescence output into AI-2 concentrations by using the developed standard curve. Data represent the means of two cultures per Y. pestis strain (A), means ± standard deviations of two cultures with 4 wells per time point (B), and the same data as in panel A with bioluminescence converted to μM by using the curve in panel B (C).