Fig. 4. E. huxleyi strain-specific DMSP exudation and susceptibility to Sulfitobacter D7.
(A) Concentration of DMSPd in media of monocultures of four axenic E. huxleyi strains (379, 1216, 373, and 2090) at different stages of growth. (B) Growth curves of Sulfitobacter D7 in CM obtained from E. huxleyi cultures from (A) at 11 days of growth. (C to F) Differential dynamics of cocultures of Sulfitobacter D7 with a suite of E. huxleyi strains. Time course of algal and bacterial growth (left and right axes, solid and dotted lines, respectively) in monocultures (gray) and Sulfitobacter D7–infected (green) cultures of E. huxleyi strains (C) 379, (D) 1216, (E) 373, and (F) 2090. No bacterial growth was observed in control cultures. Defined phases (1 to 3) of pathogenicity are denoted. Results represent average ± SD (n = 3). Error bars smaller than the symbol size are not shown. Statistical differences between strains in (A) were tested using one-way ANOVA for each time point, followed by a Tukey post hoc test. *P < 0.001 for the differences between all strains on day 11. P values in (B) to (F) were calculated using repeated-measures ANOVA, followed by a Tukey post hoc test. (B) P < 0.001 for the differences between all CM. (C to E) P < 0.001 for the differences between control and cocultures. (F) P < 0.001 only for the differences in bacterial growth between control and cocultures.