FIG 3.

Zinc is required for the P. aeruginosa-induced enhancement of S. sanguinis growth. (A) Growth of wild-type S. sanguinis and zinc transporter mutants with P. aeruginosa in media with or without addition of zinc at the indicated concentration. Statistical significance was assessed by one-way analysis of variance (ANOVA) with a Tukey’s multiple-comparison test, and different letters indicates statistically significant differences (P < 0.05). Identical letters indicate no significant difference. In this and all subsequent panels, the SSA designation indicates the wild-type gene, while the Ssx designation indicates a mutation in that gene, using the convention reported in the original description of these mutant strains (60). (B) Complementation assays with the zinc transporter mutant strains. Significant differences in growth compared to the uncomplemented vector control are indicated. *, P < 0.05; **, P < 0.01 (Student's t test). (C) Growth of indicated S. sanguinis strains with P. aeruginosa on CF airway cells in the presence or absence of 1 μM zinc. Statistical significance was determined by one-way ANOVA with a Tukey’s multiple-comparison test. Different letters indicate statistically significant differences (P < 0.05). Identical letters indicate no significant difference. (D) Growth of indicated S. sanguinis strains in monoculture on CF airway cells in the presence or absence of 1 μM zinc. Data are representative of three experiments performed in triplicate, and none of the differences are significant.