FCdiene concentration reached 161 mg/L and 320 mg/L at 44 h. As a result improvements in cell concentrations up to 246% could be achieved and FCdiene yield increased up to 2.8X in the first 28 h. This reduced overfeeding and the consequent, ethanol production. We implemented a new exponential glucose feed profile in a 1.8 L stirred tank reactor.
This study focuses on the establishment of fed-batch fermentation for FCdiene production because fed-batch cultivations using FeedBeads® indicated that limiting glucose supply could increase yields of biomass (1.07 gCDW/gGlucose instead of 0.20 gCDW/gGlucose) and FCdiene (21.54 mgFCdiene/gGlucose instead of 9.74 mgFCdiene/gGlucose) in shake flask scale and may have implications for larger scale processes. However, it is widely known that fed-batch processes can significantly improve product titer in yeast fermentations. Production of FCdiene using a genetically modified Saccharomyces cerevisiae has been previously demonstrated with batch cultivations with a product concentration up to 10 mg/L. Furthermore, the impact of the properties of the terpene synthase on the fermentation yield is discussed, and the preliminary studies on the engineering of this key enzyme are presented.įusicocca-2,10(14)-diene (FCdiene) is a diterpene which is interesting as a precursor of the anti-cancer drug fusicoccin A and therefore for pharmaceutical applications. Under fed-batch conditions, the fermentation yield was reproducibly increased to approximately 20 mg/L. In addition, the fermentation process seems to be improved under oxygen limitation conditions. The suppression of biosynthetic by-products via medium optimisation was found to be an important aspect. Here, we show experiments towards the identification of bottlenecks in this process. Recently, we introduced a metabolically engineered Saccharomyces cerevisiae strain to enable the heterologous fermentation of the shared fusicoccane–diterpenoid precursor, fusicocca-2,10(14)-diene. The access to fusicoccanes from natural sources is scarce. Besides herbicidal effects, these compounds also show apoptotic and anti-tumour effects on mammalian cells. A promising but so far insufficiently explored family of terpenoids are the fusicoccanes that comprise a characteristic 5-8-5 fused tricyclic ring system. A variety of different applications render terpenes and terpenoids attractive research targets.
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