Reconstitution of biosynthetic machinery of fungal polyketides: unexpected oxidations of biosynthetic intermediates by expression host.

Reconstitution of whole biosynthetic genes in Aspergillus oryzae has successfully applied for total biosynthesis of various fungal natural products. Heterologous production of fungal metabolites sometimes suffers unexpected side reactions by host enzymes. In the studies on fungal polyketides solanapyrone and cytochalasin, unexpected oxidations of terminal olefin of biosynthetic intermediates were found to give one and four by-products by host enzymes of the transformants harboring biosynthetic genes. In this paper, we reported structure determination of by-products and described a simple solution to avoid the undesired reaction by introducing the downstream gene in the heterologous production of solanapyrone C.