Biosynthetic Diversification of Fidaxomicin Aglycones by Heterologous Expression and Promoter Refactoring.

Fidaxomicin (Dificid) is a commercial macrolide antibiotic for treating Clostridium difficile infection. Total synthesis of fidaxomicin and its aglycone had been achieved through different synthetic schemes. In this study, an alternative biological route to afford the unique 18-membered macrolactone aglycone of fidaxomicin was developed. The promoter refactored fidaxomicin biosynthetic gene cluster from Dactylosporangium aurantiacum was expressed in the commonly used host Streptomyces albus J1074, thereby delivering five structurally diverse fidaxomicin aglycones with the corresponding titers ranging from 4.9 to 15.0 mg L -1 . In general, these results validated a biological strategy to construct and diversify fidaxomicin aglycones on the basis of promoter refactoring and heterologous expression.