Stimulation of alternariol biosynthesis by zinc and manganese ions

Production of the polyketides alternariol and alternariol methyl ether by mycelia ofAlternaria alternata is absolutely dependent on an adequate concentration of Zn2+ in the culture medium. Minimal alternariol synthesis occurs with 1.0 μM Zn2+, and concentrations between 10 and 100 μM stimulate alternariol synthesis maximally. Mn2+ acts synergistically with Zn2+ to provide a further threefold stimulation of alternariol synthesis. The relationship between Zn2+ stimulation and light inhibition of alternariol synthesis is discussed.