Figure 5. Aflatoxin and kojic acid production assays.

Thin layer chromatography of liquid culture medium from the cultured isolates was performed for aflatoxin B1 (A) and kojic acid (B) with UV excitation at 365 and 254 nm, respectively. Aflatoxin was produced by the toxigenic isolates only in YES (yeast extract sucrose) while no aflatoxin production was observed for K54A in either medium. Kojic acid was shown to be produced by all isolates at a higher level in YEP (yeast extract peptone) than in YES (B), and seemed to be stimulated by the addition of H₂O₂ (C). In the solid medium assay based on Bentley⁶⁶ (C), the low production of kojic acid by K54A in the solid culture assay may be due to compositional differences in PDA and YES. Images are representative of three experimental replicates.