FIGURE 5.

Effect of PykA activity on the survival of V. vulnificus against H₂O₂ stress generated by its fungal neighbors in the presence of glucose. (A–D) Wild-type V. vulnificus CMCP6 (squares), the pykA mutant (triangles) and the complemented strain (circles) were inoculated in (A) fresh M9S medium containing 0.2% glucose, (B) the cell-free culture filtrate of A. fumigatus grown in M9S medium containing 0.2% glucose, (C) the cell-free culture filtrate of A. welwitschiae grown in M9S medium containing 0.2% glucose, or (D) the cell-free culture filtrate of A. welwitschiae grown in M9S medium containing 0.2% glucose and 1 mM sodium pyruvate. Bacterial growths were then monitored by measuring the optical density at 600 nm and presented as the mean ± standard deviations (n = 3). (E) The indicated strains of V. vulnificus were cultured alone (1–3) or with A. welwitschiae (Aw, 4–6) in M9S medium containing 0.2% glucose. The overnight cultures were serially diluted fourfold and 1.5-μl aliquots were spotted onto TCBS (thiosulfate-citrate-bile salts-sucrose) medium containing 2 μg/ml tetracycline. (F) The H₂O₂ levels in culture media from (E) were determined using the hydrogen peroxide assay kit (BioVision). The results are presented as the mean ± standard deviations (n = 3).