In this study, an attempt was made to evaluate potential industrial sources of precursors for nikkomycin production, such as fermentation wastes and microbial biomass. Production of nikkomycins (nucleoside antibiotics inhibiting chitin synthesis) by Streptomyces tendae (ATCC 31160) on the basal soymannitol medium was considerably enhanced by addition of fermentation wastes of Bacillus thuringiensis var. kurstaki (HD 263), which contained about 0.8 g/l of various nucleosides and bases (uracil 0.43 g/l; hypoxanthine 0.21 g/l; as well as uridine, cytosine and adenine). Effects of different precursors (glucose, uridine, yeast RNA, Escherichia coli powder) on nikkomycin yield and composition were investigated: glucose addition significantly improved fermentation performance; uridine added to the basal medium increased Nk Z production and suppressed Nk X, but no such inhibition was observed in glucose-containing medium; yeast RNA was a more potent inducer of nikkomycin biosynthesis; E. coli powder resulted in considerable yield but low biological activity due to more tripeptide analogues (Nk I and J). Combination of uridine and B. thuringiensis broth further increased total nikkomycin yield. HPLC analysis showed uridine was taken up during exponential growth, uracil accumulated after exponential phase, and both were rapidly taken up from day 6. The recent boom in B. thuringiensis larvicide production makes recycling of its fermentation wastes (rich in protein and nitrogen bases) practical and economically desirable.