Alanine is a precursor in the biosynthesis of fumonisin B1 by Fusarium moniliforme

The biosynthesis of fumonisin B1 by Fusarium moniliforme was studied in liquid culture. Stable isotope labeled alanine was added as a precursor to static and shaken cultures of F. moniliforme. Incorporation of 13C and 2H labeled L-alanine into fumonisin B1 was measured by GC-MS. Under static culture conditions, 20.8 micrograms ml-1 of FB1 were produced with a 5.5% level of incorporation of intact, labeled alanine into fumonisin B1. Under shake culture conditions, much higher levels of fumonisin B1 were produced with levels reaching 159-240 micrograms ml-1 by 21 days after culture initiation. A lower level of alanine incorporation, from 1.1-1.4%, was observed under these conditions. Under shake conditions, incorporation of labeled alanine was reduced because of the rapid metabolism of these cultures combined with the high level of fumonisin B1 production resulted in rapid turnover of the added, labeled alanine and reduced percentage of incorporation. The evidence presented indicates that alanine is incorporated intact into fumonisin B1.