PRODUCTION OF [C-14] FUMONISIN-B(1) BY FUSARIUM-MONILIFORME MRC-826 IN CORN CULTURES

Kinetics of growth and fumonisin production by Fusarium moniliforme MRC 826 in corn ''patty'' cultures were investigated, and a technique was developed for the production of [C-14]fumonisin B1 ([C-14]FB1) by using L-[methyl-C-14]methionine as the precursor. A significant (P < 0.01) correlation exists between fungal growth and FB1 (r = 0.89) and FB2 (r = 0.87) production in corn patties, beginning after 2 days and reaching the stationary phase after 14 days of incubation. [C-14]FB1 was produced by adding L-[methyl-C-14]methionine daily to cultures during the logarithmic phase of production. Incorporation of the isotope occurred at C-21 and C-22 of the fumonisin molecule and was enhanced in the presence of unlabeled L-methionine. Although the concentration of exogenous unlabeled methionine is critical for incorporation of the C-14 label, optimum incorporation was achieved by adding 50 mg of unlabeled L-methionine and 200 muCi Of L-[methyl-C-14]methionine to a corn patty (30 g) over a period of 9 days, yielding [14C]FB, with a specific activity of 36 muCi/mmol.