FIG 3.

Toxoflavin production is compromised in the B. glumae ΔdbcA strain. (A) Visual observation of toxoflavin (yellow pigment) produced by B. glumae 336gr-1 and the ΔdbcA strain on an LB agar plate after growth at 37°C for 72 h. Left and right panels of the figure indicate toxoflavin produced by the B. glumae 336gr-1 and ΔdbcA strains, respectively. (B) Quantification of toxoflavin production by the B. glumae 336gr-1 and ΔdbcA strains on LB agar plates. (C) Quantification of toxoflavin production in LB broth medium over time. B. glumae 336gr-1 (black bars) and the ΔdbcA strain (gray bars) were grown in LB broth medium buffered with 70 mM Tris (pH 7.0) at 37°C with shaking for 42 h. Toxoflavin levels in the culture medium were determined at 6-h intervals. (D) Complementation of toxoflavin production in the B. glumae ΔdbcA strain. Indicated strains were grown in LB broth medium buffered with 70 mM Tris (pH 7.0) without addition of antibiotic and rhamnose at 37°C with shaking for 30 h. (E) Analysis of toxoflavin produced by B. glumae 336gr-1 and the ΔdbcA strain after 30 h of growth by TLC. *, P < 0.05; **, P < 0.01; ***, P < 0.001.