The biosynthesis of bellenamine was studied by feeding 13C and 15N labeled precursors to the synthetic medium culture of Streptomyces nashvillensis MD743-GF4. The high degree of incorporation of D-[1-13C]beta-lysine indicated that it is a direct intermediate, while supplemented L-beta-lysine repressed the production of bellenamine. [2-13C]Glycine was well incorporated into the C-1' of the open-chain aldoaminal structure. All four nitrogens of bellenamine were derived from [15NH4]2SO4 present in the synthetic medium. In the addition of L-lysine and glycine, [15NH4]2SO4 was highly incorporated into CONH. The feeding experiments of 13C labeled acetates suggested that the D-beta-lysine moiety was derived from L-lysine by catalysis of a new 2,3-aminomutase, and L-lysine was biosynthesized from acetates via the TCA cycle and diaminopimelic acid pathway.