FIG. 3.

TLC of extracts of CS10 and omtA-disrupted strains LW1418 and LW1432. (A) TLC of extracts of CS10 supplied with (fed) exogenous O-methylsterigmatocystin (OMST). Lanes 1 and 7, aflatoxin B₁ (AFB₁), AFB₂, AFG₁, and AFG₂ standard mixture; lanes 2 and 6, OMST standard; lane 3, CS10 fed no pathway intermediate; lane 4, CS10 fed sterigmatocystin; lane 5, CS10 fed O-methylsterigmatocystin. Ten-microliter samples were analyzed using chloroform-acetone (95:5) as the solvent system. (B) TLC of extracts of omtA-disrupted strains LW1418 and LW1432 supplied with (fed) exogenous sterigmatocystin (ST) or OMST. Metabolic scheme for aflatoxin biosynthesis in strain LW1418 and LW1432 is shown at the top of the thin-layer chromatograph. The ver-1 and omtA genes involved in aflatoxin biosynthesis are nonfunctional in LW1418 and 1432. Lanes 1 and 8, OMST standard; lanes 2 and 7, AFB₁, AFB₂, AFG₁, and AFG₂ standard mixture; lane 3, LW1418 fed OMST; lane 4, LW1418 fed ST; lane 5, LW1432 fed OMST; lane 6, LW1432 fed ST. Ten-microliter samples were analyzed using ether-methanol-water (96:3:1) as the solvent system. Abbreviations: VA, versicolorin A; DMST, dimethylsterigmatocystin.