FIG. 4.

Production of AI-2 by B. burgdorferi. Strains 297 (wild type) and AH309 (luxS) were diluted into fresh medium and grown for 1 to 7 days at 34°C. Culture densities were determined using a Petroff-Hausser counting chamber and are illustrated as a growth curve. V. harveyi reporter strain BB170 was cultured with each B. burgdorferi culture supernatant, and induced luminescence recorded. Values illustrated are those determined following 3 h of incubation. Luminescence values obtained for the negative control AH309 supernatants were subtracted from corresponding values obtained for strain 297. Statistically significant (>90% confidence interval by independent sample t test) mean luminescence values are illustrated as grey rectangles. Error bars represent standard deviations of two to five separate experiments.