Influence of dimethylsulfoxide on tylosin production in Streptomyces fradiae

The polyketide aglycone, tylactone (protylonolide), does not normally accum ulate during tylosin production in Streptomyces fradiae, suggesting that th e capacity of the organism to glycosylate tylactone exceeds the capacity fo r polyketide synthesis. Consistent with this model, tylosin yields were sig nificantly increased (due to bioconversion of the added material) when exog enous tylactone was added to fermentations. However, tylosin yield improvem ents were also observed (albeit at lower levels) in solvent controls to whi ch dimethylsulfoxide (DMSO) was added. At least in part, the latter effect resulted from stimulation of polyketide metabolism by DMSO. This was reveal ed when the solvent was added to fermentations containing the tylA mutant, S. fradiae GS14, which normally accumulates copious quantities of tylactone .