Requirement of Ca2+ for aflatoxin production: inhibitory effect of Ca2+ channel blockers on aflatoxin production by Aspergillus parasiticus NRRL 2999

Aflatoxin production by Aspergillus parasiticus NRRL 2999 was inhibited whe n Ca2+ channel blockers, i.e. verapamil and diltiazem(> 1 mmol l(-1)), were included in the culture medium. Inhibition was not accompanied by growth i nhibition, nor was the [C-14]-glucose uptake by the organism altered. Howev er, both the compounds inhibited [C-14]-acetate incorporation into aflatoxi n B-1 in a dose-dependent manner and decreased sporulation of the organism. Even though a nutritional role for Ca2+ has not been demonstrated unequivo cally in fungi, the present study suggests the importance of Ca2+ in the pr oduction of these secondary metabolites.