Biosynthesis of aspinonene, a branched pentaketide produced by Aspergillus ochraceus, related to aspyrone

Abstract

Feeding experiments with [¹³C]-labelled acetates and [¹⁸O₂] to Aspergillus ochraceus(strain DSM-7428) have been carried out to evaluate the biosynthesis of aspinonene 1. The results reveal a close relationship to aspyrone 2. After a rearrangement reaction of a pentaketide intermediate the hypothetical bisepoxide 5 is either oxidised leading to 2, or reduced leading to 1. Both pathways were found to be active in A. ochraceus, and could be directed towards 2 by using increased dissolved oxygen concentrations during fermentation.