Kinetic modelling of the biochemical 9-octadecenedioic acid production and lipid accumulation using differently functionalised C18:1 substrates

Abstract

The potential use of different hydrophobic substrates (oleic acid, oleyl alcohol, methyl oleate and rapeseed oil) for the production of high concentrations of 9-octadecenedioic acid by the genetically engineered C. tropicalis ATCC-20962 yeast was researched. For comparison purposes, data for growth, intracellular triacylglyceride (TAG) accumulation and dicarboxylic acid (DCA) production were obtained for mathematical description using both known and newly adapted models. Fermentations were carried out in an aerated, stirred 2L-fermenter in which temperature (30°C) and pH (8.2) were controlled automatically. Using oleic acid resulted in the highest DCA production, i.e. 31.3 g.L−1 in 144 h, as well as the highest intracellular TAG concentration (60.5 m%). Mass balance calculations proved that 35 % of the consumed oleic acid was used for TAG accumulation. The oleyl alcohol and rapeseed oil substrates showed high initial DCA production rates as well, however, after 80 h, DCA production stopped to reach a maximum. In contrast, with methyl oleate substrate, a very slow production was observed without approaching a maximum within the experimental time.