Abstract
The factors involved in the selective accumulation of ansamitocins P-2, P-3 and P-4 by Actinosynnema pretiosum subsp. pretiosum No. C-15003 (Synonym : Nocardia sp. No. C-15003) were studied. The production of ansamitocin P-2, with a propionyl moiety at the C-3 position of the ansa chain, was stimulated more than 3-fold by the addition of isoleucine, propionate, propionaldehyde and n-propyl alcohol to the fermentation medium. The production of ansamitocin P- 3, with an isobutyryl moiety, was enhanced by the addition ofvaline, isobutyrate, isobutyraldehyde and isobutyl alcohol, and the proportion of P-3 reached more than 90% of the total ansamitocins produced. The production of P-4, with an isovaleryl moiety, was stimulated by leucine, isovalerate, isovaleraldehyde and isoamyl alcohol. The radioactive compounds, which selectively stimulated the production of each ansamitocin component, were preferentially incorporated into their respective acyl moieties of ansamitocins. Based on these results, we propose that the acyl moieties of ansamitocins P-2, P-3 and P-4 are derived not only through catabolic pathways of the respective amino acids, but also directly from alcohols, aldehydes and fatty acids having the same number of carbon atoms as those of the acyl moieties.
